There are no in-game classes, you just buy whatever weapons, equipment and vehicles you want. The only soft limit is the cost of items, and I assume that's something they're going to continue adjusting. The different classes only exists out of game, where you have different XP tracks. I.e. to unlock more sniper weapons and equipment you have to do sniper-y stuff while playing first.

At least the early assault rifles which I had access to in the beta were pretty crap at range, so IMO it has less of the "everybody is a sniper" feeling of HLL :D I think any semi-realistic game with a huge map tends to naturally favour sniping to some degree.

Never played Bf1 but afaik there is not limit to weapon purchases per team