No worries about the queries. I'll try to answer them in order.
The seat was completely rebuilt by a guy in San Antonio Texas who specializes in scooter and motorcycle seats. He uses a foam imported from Germany that does not seem as hot as memory foam and is definitely more comfortable. I removed the stock seat after he made measurements according to my specs; I wanted it cut lower and narrower and softer. I chose the colors from his swatches, and added the trim. More custom touches on the way as I love my X500 - except for the name, Xciting.
The saddlebags I found online after a week of searching through various online and instore selections. I think I found them on ebay. I don't usually shop there as too much ebay stuff is cheap and doesn't last.
The backrest is made by a guy here in Austin - Jac Vinsen, I believe that's his name. The stock backrest comes out, remove a couple of screws and it is off the stock bracket and mounted on the taller backrest. Takes about 5 minutes to swap them.
I don't usually ride with the tall backrest, only on long trips, longer than a day or two. I prefer the way the scoot handles with stock, seems more nimble. About 2/3 of my riding is around Austin or perhaps 100 miles out for a day trip. These roads in Central Texas are windy and hilly and tons of fun on two wheels. We do have freeways, I prefer the back roads for scenery and fun.
And yes, the tall, custom backrest is also adjustable as it mounts the same way.