Ah ok, so you just sleeved it then?
That is #4 solid copper (props on the keen eye) I ran it over and grounded it on my water service while I was working that wall.
What did you bond your water meter to on the other end? Gas line? Water line?
I'D like to hire someone for the weatherhead and meter (poco doesn't handle meter?) As that side of the box kinda terrifies me but as you can imagine I've got plenty of other shit I need to spend a grand or two on. Also I'm under the impression that if a licensed electrician touches your system they have to bring it all to code which may total my house out.
Both sides aren't much different at all, honestly. And the problem with you replacing the panel and having someone else do the meter side is that it's much easier to do the panel while doing the meter. If you do the panel yourself you'd prob want to pull the meter bubble so you aren't trying to reland the panel with hot service conductors, and in the last decade or so power companies have been making it more difficult to pull meters w/o jumping a lot of hurdles. Back when meters were just the 'spinning dial' type we'd pull meters whenever we wanted; now a lot of the newer ones actually report remotely and the utility knows when a meter is removed. That isn't everywhere but /shrug.
If you don't want to hire an electrician for all of it, give your utility a call and ask them what their procedure is for pulling meters and homeowner stuff. If they'll pull the meter for you on request then great, have them do that and then you can do the service panel. Some places will charge you to install a temp drop from the triplex and then actually cut your service at the service point (like, where the overhead triplex splices to the homeowner's cable at the roofline in your case) so that it's dead for the duration but you'll have a few receptacles to run cords to freezers and the like. Then you call them when you're finished and they come back to remove the temp and reconnect.
Utilities usually do not supply metering equipment (the box) for residential but yours may be different, you'll have to ask them. Normally the only time they supply metering equipment is CTs (current transformers or "donuts" for non-Resi), transformers, and occasionally the CT cabinet. I cant think of a time I ever had to get a meter can from a utility for Resi, and they've never installed anything.
As far as getting an electrician and being forced to do a bunch of additional work...the way that works is that let's say an electrician opens up a wall and finds some scary wiring. They'll have to replace all of that as that is now exposed work, and anything that they work on DIRECTLY they are responsible for getting up to code. But wiring in other rooms, attics, kitchen, etc, they won't need to replace. This is why I've also had builders beg me to "fish" wiring through walls rather than tear the plaster or sheetrock out first on remodeling jobs: if you just fish it, wiring isn't exposed and you don't have a responsibility, but as soon as you open up a wall, if you see something wrong then yeah you have to fix whatever you find before the wall is then closed back up with sheetrock. This is especially common in remodeling old homes with knob and tube, people just want to do the bare minimum and not gut an entire building and if you start exposing knob and tube then that shit has to be replaced (ugh).
So as it pertains to your service: if they just do the panel, they will have to address things like grounding and bonding (your #4 bare, water meter, equipotential jumper @ water heater, ground rod and GRC, etc) and everything inside of the panel itself. This shit IS important and should be done. But as far as the rest of the house, romex, old wiring etc, they won't have to do much (if anything) beyond relanding them in the new panel (preferably with connectors this time *cough*). Anyone telling you that they now have to rampage through your basement or house replacing branch circuit wiring is straight up bullshitting you and you should kick that asshole out of your house and call someone else. They can make honest suggestions and tell you how much of a nightmare your wiring is or how dangerous it might be, but they can't make you allow them to rewire the entire house, LOL.
If you decide to do the panel yourself, do as I suggested above and contact the utility and do the panel swap before an electrician does the meter and drop. This way they'll do the meter, riser, and service conductors from the meter to the panel and they'll just connect the new service conductors to the panel you installed (probably with conduit between the meter and panel if they aren't shitty electricians, especially with the block wall). If you don't have the panel done first you risk the electrician running larger conductors than can be landed in the old panel and at that point you'll be forced to let them do the panel as well. If you put in a new panel first (say a 200A) for the extra spaces, more than likely the new panel will be rated for a range of conductor sizes so that regardless of what they end up doing with the new metering (100a, 150a or 200a) they should be able to have the new service conductors fit in the panel lugs (though it's always good to check the panel specs for the wire sizes that it is rated/listed for first). 4/0 is the absolute largest you should see (200a, aluminum cable) down to maybe a #4 with #2 Nuet (assuming 100a service drop, copper conductors).
You can also call an electrician and have them quote you for the entire service (panel + meter), for just the meter and for just the panel. They can keep the service cable normally if they do just the panel first, you let them worry about fiddlefucking around with the utility, have them install a 150a or 200a QO panel (or buy one yourself and hand it to them) and then you can replace the 100a metering at a later date. So pay for a panel swap now, have them come back out for the service 6-12 months down the road or whatever. They'll want to do the meter at the same time (I would) but normally if you're only replacing a panel then the "panel" is the scope of the work and unless there is something immediately dangerous they wont have to do the meter right then. I honestly would suggest trying this - call, have guys come out and give you quotes, tell them that you cant afford meter + panel right now (normally a lack of funds is pretty important as electricians don't like not getting paid lol) and see what they want for just the panel now and the meter later on down the road. Worst case scenario they all try to force you to do meter + panel at once, at which point you can shrug and tell them thanks, I'll give you a call 'sometime' (at which point they might bend if it looks like they may lose the work). If they don't bend, call someone else for an estimate or do it yourself.
And no offense, but after seeing the romex entered w/o connectors I really don't want you replacing your own panel LOL.
Also you do have to size the service for the load served (or that will be served in the foreseeable future), and if you haven't added a bunch of shit (doesn't look like you have) then putting a 200A panel on an existing 100A meter/service drop should be fine. Where electricians get nervous is when they swap a panel from 100a to 200a w/o changing the meter and they worry about a homeowner adding an arc welder, a hot tub and a garage full of extra power tools (motor loads from table saws, etc). You have the possibility for someone putting "200amps" worth of loads on the new panel being served by a 100a meter and having shit burn your house down (for realzies). There are a couple ways to figure out what your load is and to size your service accordingly but unless you plan on adding shit you should be okay.