1. If your just doing a maintenance wash you don't nee to use detail spray.
2. After I've done a full detail I just do a normal 2 bucket wash and every 2-3 months I seal the car again.
3. Yes you can apply Americana with a DA. I use a 5.5 and a 4 inch pads.
4. Depends on weather conditions. I mostly use sealants in seattle cause the weather sucks here.
5.I only do IPA wipe down when polishing. Just use a dawn mix of Adams/dawn.