Ghost 100%. And I agree with Eric F. Get in touch with Core. He's awesome, and you'll be very happy. You might consider getting a new bat every year instead of trying to make it last until middle school, especially since she's already hitting bombs.
Stationary hitting is most important. Seeing as many balls from the left side is huge. If she can hit well to all fields, then slapping will come easy. Work on foot speed now if she wants to slap down the road.
Someone should do the legwork to get some old high school turf donated to that place. That would be a phenomenal indoor facility with turf. I am here in the greater Seattle area also, and we've had two indoor facilities that got the old HS football turf and it has worked out awesome!
I have never heard of a guest player having to pay anything. Usually a guest player is there to help the team for the weekend(s). The teams budget for the year should have already been covered. Maybe a cost for extra uniforms?
Agree lefty. My DD made the switch full time at first year 14u. Yours looks like it will be a way smoother transition than ours. Its paying off bigtime now 3 years later, but that first year was a process, to say the least.