You're doing the right thing- giving a lot of thought to this. As far as risks buying at a show- good sellers won't allow handling of their animals unless one is a serious buyer, & washes hands.
There's pros & cons no matter how you purchase a snake- lots to be said for seeing it in person first, but all it takes is one seller that shows up with mites on their animals & they can manage to share them because they're just so hard to see, & so many people to spread them. It happens.
It is hard to think of everything when examining animals- I'd suggest taking a list of things to check (health wise & questions you want answers for), & a good breeder will provide the date of hatch, & specifics about what & how they're being fed- ASK! Nothing worse than getting a snake that refuses to eat because it's the wrong thing (rat or mouse? Size?) or offered the wrong way (live, f/t, fresh killed, drop-fed?) It's all about being prepared. It also helps to know how much space a snake has been raised in- going from tight quarters to a large enclosure can freak some snakes out, & when you first bring home a snake, it eases the transition considerably if you copy how it was cared for previously as much as possible for a while.
Finding reptile-friendly apartments- unfortunately that might not be easy.