i've 100% solo queued so far and no problems, don't worry too much about winning and its not a big deal. you'll get teams with good players who know what to do, and sometimes you'll get noobs who play like its team deathmatch. grouping up has its own issues, like preferring matches against other similar sized groups - no big deal if its just 2 but then you get sweaty games or go up against a full 6 man premade, which won't happen with solo queues. the big advantage of group queues is not getting bored, it is pretty boring solo queuing up but I've been watching twitch streams to learn some of the classes.
whats really fun is just trying out different classes, lot of noobs still so its super easy to wreck face as bastion, sitting in one spot and ass raping runners. I'm sure in a day or two people will get the counters in (genji) but for now its insane
you can buy loot boxes for $2/each and discounts in packs, its $40 for 50 loot boxes. don't see the point really though, you get 1 per level and its pretty fast leveling. played about 4 matches and level 5 already.