Not sure if I get the question. Ham radio isn't channelized.
Take 20meters which is a popular band for DX (contact at a distance, like talking from country to country.
It starts at 14mhz and goes to 14.350mhz. The voice portion goes from 14.150 mhz to 14.350mhz and that is further broken up license class.
So let's say from 14.150 to 14.350 just to talk. You can basically have someone talking 3khz apart so 14.150 then 14.153, 14.156 or 14.155 if someone isn't on 14.153 which would bleed over into your frequency.
So to find someone you basically start wherever and spin the dial listening, you might hear 2 people talking, one person calling CQ which means he is looking to talk to someone (they might say CQ DX which means I want to talk to someone from outside my country) or CQ Pacifc, CQ North America etc.) or someone calling QRZ which means they are just taking as many contacts as possible as fast as possible.
I'm not sure what you mean by number stations. Nobody has a frequency assigned to their station. If I want to talk to someone I just spin the dial in the appropriate band in the part I am licensed to use and find one someone isn't using. I might call CQ and get someone from a few states away or Eastern Europe or anywhere. Same for them. There are nets which meet on X day at Y time on certain frequencies and they take turns talking and such. Honestly that's where the real old guys hang out but they've known each other for 40 years or more. I guess before the internet it was a great place to find out the weather because when they check in they give their call sign, location and what the weather is where they are. The only net I check into is the martime mobile which gives the gulf update and the hurricane prepardness one which meets one night a week for just a few minutes as long as no storm is active.
It basically comes down to courtesy and common sense. No assigned channels or frequency to a station. A special event station just means they get a special callsign for the event, normally part of it will have to do with their event.
There are webites you can report a "spot" which list the callsign and freq. You can sort by band, special stations, or continent or even country. Only rare or special stations really get a spot. Like in the US North Dakota gets a spot, there are fewer ham radio operators there than any other state and people want them in their log so they can get an "all worked states" award. They also give out awards for 100 countries and multiples after that. There's a service that confirms your contact in your logbook with the ones other submit to keep it on the up and up.
There are all kind of awards. I talked to a guy in the Czech republic that was trying to work all counties in the US. He already had mine. He has an entire ranch that looked to be 100 acres on his site of nothing but antennas. He even floods a portion of it with saltwater because it increases the conductivity of the soil which helps some types of antennas. Those are the hardcore. Some people try to get all grids in a certain country. I think there are like 9000 grid squares in the US alone.
Me I just talk to people and try for odd stuff like Anartica etc...I plan to try for the International Space Station again, they send out QSL cards as well which is cool.
The commonwealth games speecial event station in Scotland was GA14CG. The special event station at the Indy 500, Brickyard 400 and the MotoGP race at Indy was W9IMS. Every weekend there's a ton of them from state fair deals to tonight I heard one from South Cook Island talking about something to do with the 150anniversary of Canada or some meeting to do with it. I had a hard time keeping up.
These are the type of contact cards you get from special stations. Here's the one from Indy Motor Speedway from last year for the Indy 500, Brickyard 400, and the MotoGP race.
This is my temporary card I send. I'm still in recovery mode living with my parents for another month or two. I have a better one from the state I actually live in. The state on this one isn't right either but I got someone on a forum to make it for me then I PM'd him the actual info so my callsign wouldn't be everywhere with my real name and adress.