Not sure about the prices of skip potions cause it's been awhile since I bought one for my alt but there is a sale goin on in the mogstation( this game's cash shop) for alot of items and may include skip potions but I'm not sure so you'd have to check, I think the price of the skip a real reborn story one is like 15 bucks and to skip arr and hw that one I think is 25 bucks.

The primal battles you're talking about aren't that hard at all so you'll be fine, just throw up an unsynced party finder and put 1st time bonus in it and you'll be good to go or if have friends or are in a free company have them take u through real quick.

The grind from 2.0 to 3.0 yes it's like u heard but you can always buy a story skip if u don't wanna do it and just go to an inn and watch most of the cutscenes u missed.th