Flying for first time ever in business class. Have a few questions:
1. When flying economy I have almost never used the FA call button. Is it more acceptable in business to use the call button?
It can be a touchy subject. Some US carriers tell passengers it's for emergency use only, which is BS. If no FA's are about, and you need something, use it. If not a hurry, wait until they pass by again.
2. Are lounge access and expedited security lines automatic at departing airport or should I enquire at check-in for lounge pass?
For international flights they often give it to you when you get your boarding passes. For a domestic connector, you may have to ask if you have access.
3. Silly question but how hard is it to figure out the operation of the business class seats and is it fine to ask FA for help in figuring out?
Sure, they are mostly happy to help. Most are pretty easy to use, though.
4. What requests are acceptable and what requests are not? For example, is it okay to ask to keep the robe as a souvenir?
They do give pajamas out on some routes. Usually only in First Class, and you are free to take them with you. Most biz class flights these days do not give them out.
5. Any tips on fitting into the business class atmosphere? Usually I dress down while flying but would it be a good idea to dress business casual or better?
Don't be rude, and no laughing at the Y passengers as they head to the back. 
Any tips on obtaining the best experience at airport, lounges, layovers, pre-flight, inflight, etc. is appreciated. I want to enjoy the experience without coming across as overbearing. Posted in UA forum because it is UA award ticket though very little UA metal involved. Please move if necessary. Thank you very much; FT has been awesome!
Itinerary:
SNA-IAH UA 737-800 (1 hour 47 min layover in IAH) 2A
IAH-IST TK 777-330ER (3 hour 35 min layover in IST) 2A
IST-BOM TK 330 on UA but showing 777-300ER on TK (destination) 2A
BOM-NRT NH 737 (8 hour 25 min layover in NRT) 2K
NRT-LAX NH 777-300ER (home) 8K