Q1- Which one is best? I don't know. there are a lot, and you are going to pay for them. I would call a few RV repair shops and ask which ones they find easiest to deal with, or most widely accepted. As stated above, are they needed? That's up to your own mechanical abilities, and how much time and patience you have dealing with issues. Some dealers offer a "forever warranty" that only requires you do have some annual maintenance performed. We just purchased a new 5th wheel and I decided not to purchase the extended warranty. I like fixing things myself, even if they are covered, because its quicker, and I probably do a better job.
Q2- That is usually a separate component and an up charge to the roadside service plan. What I chose to do is make sure I have good tires, religiously check tire pressures, and watch them with a TPMS. I make sure my spare is good. I carry a wedge style jack so I don't have to mess with "jacking" the rig up. I carry a battery powered impact gun to insure a quick tire change. I also carry a flashing roadside emergency light.
Q3- I chose Good Sam because it was a little better priced for longer distance towing, but either Good Sam or AAA is good. Depends on your needs. Just price both out with whatever added extras you think you might need.