We love the accessible MVs! We’ve used them many times. Unfortunately the most important thing when calling one is have bus backup. There are only a couple running at a time and if they’re booked up for a couple rides you won’t be able to book one. Sometimes they arrive in a few mins, sometimes they’re just under 20 mins out. Sometimes it can take 10-20 mins just to get assigned one or find out they can’t find one for you. You already know how to take a bus back if necessary so you’re covered here. I’d start looking around the time you are settling your check.
Tipping is neither required nor expected but it is allowed. Originally it was not allowed as the drivers are salaried Disney employees with benefits and Disney felt that made this an all inclusive service but so many guests insisted on tipping Disney relented. Do as you wish in this area.
Fwiw my tipping choices:
Accessible MV: 10% as the driver does physical work to get the chair hooked in safely
Normal MV: no tip, I feel the high cost is compensation enough and excellent service is part of that charge. Once I start traveling with anyone needing car seats I’ll tip for the extra physical work that takes.
Normal Lyft: tip 15-20% as normal rideshare drivers are not salaried with benefits