I have never seen an AC powered vent top fan, but it may be because I never looked for one. Someone else out there might know of one.
As for ovens and a cook top, I am sure that you will get many different reply's as it is a lifestyle thing. Speaking only for myself, I have a small gas oven and cooktop and I almost never use them. They both generate a ton of heat inside the living space and with such a small living space it quickly becomes a problem. When it is cold, or at least cool outside I can flush the hot air with the ceiling vent fan but the hot air still hits me right in the face when I stand in front of the stove. I made a design error by not putting in a dedicated stove vent and fan. I thought the ceiling vent fan which is just a few feet away would suffice, but it is a compromise.
So, back to your question, I used the oven once just to prove that it works, and I have used the cook top only occasionally. The microwave gets the most work just because it is the most efficient way to heat something. It seems that most of my use has been in hot to extremely hot weather though. I might have a different answer if I did more cool to cold weather travel.
Oh, and I have used the stove top to heat the place up quickly (with plenty of fresh air input because it can be dangerous otherwise). My Platinum Catalitic heater is great but it generates heat slowly, which is adequate due to the excelent insulation, but takes a long time to overcome the thermal mass inside. (Same issue as with air conditioning in reverse.)
I think your truck might have a higher internal ceiling height than mine. My ceiling is just a few inches over the top of my head (tall people need not apply). Thus a layer of hot air from the stove is in my face rather than being over my head.
Unfortunately, if you want to use your microwave off grid, that implies a fairly big inverter. You can buy microwaves with a dedicated inverter built in. Be aware that a high energy device like that draws roughly 10X the current at 12VDC than it would for 120VAC. That means you will need some monster wires to carry the current, much more than a typical 15A AC house wiring application. A microwave will also draw your house batteries down quickly, but unlike an air conditioner, it only needs to run for a few minutes.
If you want to make coffee, or run a toaster, these are also things that draw a lot of current for a short time. Together they make a good reason to have a fairly big inverter, even if you never run them at the same time. The alternative, that many people favor, is to run the generator while making breakfest. That takes care of all those things and gives your batteries a boost when they need it most.
I have never had a problem running a quiet generator like a Honda EU2000i in a Walmart parking lot, or pretty much anywhere for that matter. Contractor type generators are another matter though. They are generally very loud and tend to make enemies, or at least chase your friends away. I am also told that contractor generators are not good for running things in the house as their voltage and frequency are not well controlled. I don't have any personal experience on that one though.