I haven't worked volleyball in years, and only did it for 2 years while in college, but I do work hoops and football and can shed a little light on these issues in our world.
1. In hoops, I ALWAYS change at the site. The only exception is for pre-season scrimmages when the weather is still warm and we wear shorts, and even then, I still partially change at the site. In football, it depends: I always go dressed or partially dressed to all sub-varsity games and select varsity games (sites without dressing facilities). Most HS varsity games, we dress on site as a crew. For college games, dress on site as a crew. If I were still doing
VB, I'd go dressed, but I live less than a mile from my office.
2. If I were still doing
VB, I wouldn't bother wearing additional shoes. For hoops, I'd definitely change, as my BB shoes are for work (and hopefully, indoors) only. In football, I wear sliders in the car and put the shoes on at the site while still in or around the car.
3. Equating accepting drink and even food to a bribe is stupid. I wish everyone would provide it, and I think less of those that don't. In HS and junior high football, its virtually universal for us to get something to drink, even sports drinks. In hoops, it depends on the site. For college games in both, drinks and often food are the norm.