chinese slate

i'm building a new house.   i found 16x16 chinese slate tiles (1/4" thick, or so) at a great price.  but, before i buy them,  are these tiles going to be a royal headache?   no, i'm not going to install soft slate on a countertop in the kitchen or in a full bath floor or in a shower enclosure.  but are the kitchen floor, floor in a 1/2 bath, pantry and foyer reasonable applications?  i'm guessin' an outdoor application for this porous thin tile over conscrete is ill-advised (i live outside portland, oregon and get generous frost at 1100 ft elevation) --- or is it?.  and, for the record, do i preseal before grouting?  what spacing between 16x16" tiles would u recommend?  thanks, todd