I have RV'd a lot, but never full-timed. I'd concur about all of the above. Buy the best used rig you can afford, but still be prepared to spend some time in repair shops or calling mobile repair places to send someone out to you.
Here is an entire forum of public places to "camp" that are close to major highways and interstates in the USA. Some will have the electrical hookups and water that you will need.
Donna