don't know the answer to your first question but to answer the other two; all weapons are unlocked from the start similar to Overwatch. there are no abilities, killstreaks, armour or buffs in the game. rewards for leveling up are cosmetic only.
those are Early Access price. Full release will be more but they haven't said what it'll be. if you're already thinking about buying the game you'd be crazy not to buy in Early Access. this game is going to fly.