Having been in chains on a couple of these buses during my life, I can say this much from personal experience.
In NY, you get food when your prison bus ride is more then a few hours long. We would get a paper bag with two 'sandwiches', a couple greasy cookies/biscuts ( I couldn't tell for sure), and two little cups of juice. The 'sandwiches' where two slices of bread, some mystery deli meat, and some cheese. I do not recommend trying the recipe with the ingredients they use.
Didn't matter how far you where going, that was one bag per trip per person. The trips going long distance where on converted or custom built tour buses. The seats are like what you'll find in any city bus, hard with a layer of fabric over it for the barest bit of cusion. These prison buses usually had a bathroom, but you where told it was for peeing only.
There is anouther factor as well. For the vast majority of non-guard riders, you are chained to another person not of your choosing, for the duration of the ride. Even if one of you needs to use the small single occupant bathroom. I was, in a sense, lucky. I am a large person, and the handcuff-style leg chains would not fit on me, no matter how they tried my legs where just too large and thick and only bone or muscle, so not squishy like I saw some guys who had mostly thick fat on their legs. So instead, I got what the guards jokingly called the "elephant chains", just a single chain passed around my ankles and padlocked shut so I couldn't get out. But, it meant I didn't have a 'partner'. I could have used the bathroom by myself (although I didn't, since in handcuffs I didn't think anyone would aim very well) and I had a seat all to myself, since everyone else was already forced to buddy up.
There was no entertainment, but while the windows are very heavily tinted, you can see out of them from the inside, so at least it's possible to watch what's going by. That is either a blessing or a curse, depending on the person.
And yes, we where told no talking.
Oh no, that depends on the bus. Long trips, the guards want comfort. Those buses usually have AC, maybe not pointed at the prisoners but at least the bus is cool in general. Short trips though, where the guards are up front and prisoners in the back and separate? Total crap shoot. I know this from some personal experience in the NYS system.