1. No idea, but I just increased mine to 300, so the maximum capacity is quite high. (my equipment capacity is 375, by the way, probably going to increase it to 400 next week)
2. No difference whatsoever, everybody gets the same set of login bonusses, and the same lousy chances at Gacha. The only difference is that more Flower Gems allow you to do things more often, like, use a Flower Gem for a stamina refresh, or pull the gacha more often (but still at the same price per pull)