yes. but i would not suggest it. cause after they run out you need to spend money on more. where are with syrup you can make in game and its unlimited and free (unless you buy from players)

i save and use my SP and HP bottles for when i'm questing to eat after each fight.

yes. it auto fills if you put auto eat on mote

dunno how much money you have o.o but 16p accumulates and its 30k per 16p on sale atm. and also if you buy the super bottle (only need to buy once) you'll need to fill that and keep supplying it