red knee tarantula

[Lrptls]

finally got a mexican red knee, been wanting one for years now. this is my first spider too. i'm not sure how old this one is, just keeping him in a pretty small critter keeper (quite roomy for his size) with dirt as the substrate. i just have a few quick questions...

is it ok to use a soda bottle cap with water in it to drink? or should i put something in the water like cotton or whatever they use in the pet stores?

should i give him something to climb on/hide under?

and they told me he was eating small crickets, how often should i feed him?

thanks for any answers/comments.