Ed Gee has it in a nutshell.
I agree with his responses to your direct questions as asked.
Recently switched from Directv to Dish and no complaints. Was with Directv for years but cost was significantly more than Dish. I had an issue with the MH when we switched over and called Dish, they sent out a tech to check it out. He got there and said "I'm not allowed to work on motorhomes." Then said, I'm suppored to tell you that so if you have a problem while out camping you wont' expect me to show up. Then he proceeded to fix my problem, gave some very useful suggestions and that was it.
As for channels, the only channel we don't get with Dish (that we did with Directv) is one of the National Geographic channels. I forget which one it is. Cost was over $30 month cheaper with Dish.