Tarantulas are great! Welcome to the addiction!
There's no need for a sponge in the water dish. A sponge would actually make it harder for a tarantula to drink (think of it as a human trying to eat jello with chopsticks). The only reason for something to be in a water dish is to keep crickets from drowning in it. A couple of pebbles will work for that. They do drink, and it does seem like they rarely do. Being nocturnal critters, it probably happens at night when everybody else is asleep.
Tarantulas are a bit delicate, espically when it comes to falls. I usually don't handle mine, but when I do, I always make sure I'm holding the tarantula over something soft (bed, couch cushion, pillow).
Don't be surprised if your rosehair suddenly decides to stop eating. It could be one of two things; upcoming molt, or rosehair fast. Rosehairs are famous for not eating for extended amounts of time (I have a little one that hasn't eaten in about a month).
If you haven't already, get a copy of The Tarantula Keeper's Guide by Stanley and Marguerite Schultz. It's a wonderful book, easy to read (dispite being an intimidating thickness) filled with all sorts of helpful care information about tarantulas.
Don't be afraid to ask questions or share pictures!!