Anything in particular driving your decision now? Reason I ask is sometimes people do this when they have something more serious wrong like a leak, underground plumbing issues or damaged fittings. That can complicate the project since not all bidders can diagnose, design a repair and execute it. So you might want to do this part first. Even if this is the case you'll want to define the scope of work clearly and spec out the job with a simple, written scope. Make sure you include permitting, waste disposal, access limitations, and that they specify what they'll do and what you must do in the curing process. Also make sure the contract has reasonable payment terms with a significant withholding until after the performance test is complete. Try to make sure your terms are approximately payments made for work in place not something like 80% before they start.
I like pebble and gem finishes. Many people do not. This is a 100% personal preference issue. I like the bottom to be rough enough that it's never slippery but not so rough that it tears up your feet and equipment. A lot of exposed pebbles can result in this. So if at all possible see if you can find a friend's pool or sample to try out. My brother really thought he'd want a PebbleTec finish. So he spent a LOT of money refinishing his large, gorgeous but 20 year pool with this. But he's pretty disappointed that it's so rough it tears up the tail on his pressure cleaner. Others I know feel the opposite. It's all personal preference. I love the feeling of Florida Stucco gem series. Tiny gems and rougher feeling plaster but very easy on the feet.
Last thing I'd suggest is to read up on installing and curing new plaster. There's a lot to it and installers have a wide range of expertise. Like concrete, the first 30 days of plaster life and how it's treated in this time have a huge impact on it's strength, life, and appearance. Make sure you and your installer are on the same page about this before you sign up. Here are some excellent resources:
www.troublefreepool.com
www.troublefreepool.com
I hope this is helpful.
Chris