1) nope, but cash may get you a better deal.
2) i would say it's expected. it's definitely not frowned upon unless you're just lowballing on everything and being an ass about it.
3) I go to all the tables. you never know what you'll find. a lot if times breeders you've never heard of will have the prettiest animals. plus its just fun to check everything out. its called a "show" for a reason. i go more to look at everything than strictly a shopping spree.. although those are fun as well. lol
4) not too hard. just leave them in their deli cup and keep the AC or heat on (depending on what time of the year). just make sure they dont get exposed to extreme temperatures and they'll be fine.
5) every time i've purchased frozen rodents i just pay for whatever i want and they'll hold them for me in their freezer and i just pick them up right before i leave.
have fun! shows are one of my favorite parts of the hobby