They tend to stop in each village or when flagged down. I do not recommend them for long distances, but they work fine for short hops. They may have toilets and television. These usually have TVs and toilets, and the seats are reserved. The movies on Mexican buses are usually action flicks dubbed in Spanish.
Baggage check is available.
I have yet to ride a true Lujo bus, such as the Uno line, but they look ultra-modern, and they promise lots of legroom, a stewardess, refreshments, etc. First and Plus class buses stop infrequently, usually less than once per hour. They connect cities, and do not generally stop in villages. In some cases, the higher class bus may use the expensive and faster toll road, while lower classes may use the slower free road. The price is always very reasonable, usually around 2 or 3 dollars US per hour.