building up..

I am within the first 10 floors, still getting the ropes of the game.* Later on, are healing rooms use-able only once? Also, where is there 'infinite battle' room thingers so I can max character stats? If there is one.

I am not asking for spoilers on story or anything. Just mainly where I can 'build up'.

healing rooms are every 5 floors and yes u can only use them once so you better use up ur skills before u enter.