1. Extended Warranty - Worth it only if something fails. My opinion is to take the money and put it aside to pay for any future failure.
2. Paint and Fabric - Sounds crazy pricey compared to wax and a couple of cans of Scotch-Guard.
3. Slideout Covers - If you frequently camp with slides out near trees, yes. Almost useless in the desert other than to act as a sail...
4. Power Tongue Jack - I like mine, just price shop them. Looks like they are getting $50-$75 for the install because they range in price from $213 to $270 depending on where you buy it. If you are not a handy person it's probably worth it to have it installed by them.
Welcome to the "club"!