3] It's possible to cover the distance but Raliegh is nearly 600 miles from Orlando and would be an

2] Maybe check the weather on the way out and if it's ok visit then, if not wait till you start the trip back and see if it's improved. Remember the clues in the name and mountain areas see snow. You can look at a different route each way to see new things.
3] It's possible to cover the distance but Raliegh is nearly 600 miles from Orlando and would be an extremely long day and not an ideal midway point. You once again have to take the weather into consideration and if you get slow downs/delays you would fall short anyway.
4] If you are planning to get to Key west in 3 days then I can tell you now that it's just not possible even with the best of conditions. It would be unsafe and if you arrived cheap nascar racing tickets in one piece you would be to exhausted to enjoy anything for a couple of days. Driving for 15/16 hours in one day is not recommended, to try and do it 3 consecutive days is almost suicidal. You really need 4.5 days minimum. You can find truck stops on the Interstate or look for nearby towns and search RV parks, but you should'nt plan on any more than 550-600 miles a day.
You do need to remember that your drive home will not be the only place where you have the chance of seeing severe winter weather. I-10 can and does see snow and ice, from Eastern Arizona all the way into West Texas. It doesn't get winter weather as often as some other routes, but it also takes much less snow/ice to make it a much more difficult and dangerous drive, as they are less able to deal with it and instead often take the wait a few days for it to melt approach. This may not be a big issue for this trip - since you are leaving so soon, and forecasts look clear for now - but keep it in mind in the future. Also note, it is still below freezing in these places, which may make for some cold and uncomfortable nights in an RV for your first night on the road.
If you are at all concerned about your safety - and the safety of others on the road - then you should be looking to stop around Van Horn TX, Houston, Crestview FL, and Fort Lauderdale/West Palm Beach. Those drives will already push you to about the maximum you can safely drive in a day, especially when traveling in an RV.
Yes, just realized that, Now as i am in middle of my trip, I am making some changes. Here is my fresh trip map at the moment. I am already hearing that there are snows in different location (Amarillo, texas etc.), thus, might need more changes as I go along.
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