My TT came with all those items.
Electric tongue jack: Nice, but not a priority for me. The old fashioned way takes a bit longer, and always works, battery or not.
Water heater bypass: Never used it.
Black tank flush: No. They will randomly leak at the vacuum breaker and usually will send water to places you don't want it to be. I use a flush wand that goes down the toilet.
Rubber roof: Walk on mine all the time and no issues. As said earlier, be sure to take good care of it.
Of the things you do have, all good, except maybe the kitchen. Make sure you will actually use it. My first TT had one and I found that I rarely used it and ultimately it became a storage bin more than a kitchen.
X2 on buying used. Warranty work is just a PITA; let someone else deal with the warranty problems and take the equity hit. In hindsight, I wish I had gone that route.
Good luck in your search.
