Oh wow, hi there! I'm also at SWTCC, and I work in the ASC across from Fulton building
They allow calculators and will provide one for you - it's not as powerful as the TI-83/84 models, but it gets the job done.
As for how the test goes - It's pretty close to the book; you won't see the EXACT same problems, but if you had no issue doing the problems in the book, you'll be fine on the test. The science portion I found the hardest since there was so much material to cover, and I hadn't really studied things like physics since high school (waaaay back). That being said, it wasn't too bad.
The composite score is different from percentage - you are not required to score 100% on your exam to get a score of 100 or above; on the contrary, as long as you score decently high in 2 sections, if you bomb the 3rd (I say bomb... but you'll want to aim for above a 70% in each section), I think you'll be fine.
I didn't do as well as I'd hoped and came out with a 144 - I did put in a complaint though since the proctor wouldn't stop talking while people were taking the test, so if you're easily distracted, I would wait until things settle down before starting.
As a warning - do not tab out of the exam; if you do, it will automatically stop the exam right there. One of the folks who took it alongside me thought they'd try and cheat... they ended up wasting their $75. Good luck! And if you're around after 11am, come see me in the ASC! Look for the person with the blue hair streak - let me know how you do, and I'll give you a free motivational high five