Yes you can, I have seen it done. The real world risk of a fire or explosion is pretty limited, modern cars don’t give off a lot of sparks. One issue may be that if you have an electric gas door release, there’s a chance it won’t open when the engine is running, if that’s how the car is programmed.
10 minutes of running the engine will probably charge the battery enough to start the car again, so unless the tank is really dry this might be less of a problem than you think.
Automotive locksmiths can almost always make you a new key or fob for a lot less than the dealer.
Assuming you’ll be driving a full size van (Transit, promaster etc) I hope you have experience parking this kind of vehicle. I rum a fleet of these vans for deliveries, most of the damage happens when parking. Look up - identify things the top of the van might hit like awnings, gutters, overhangs on carports and garages, etc. Then remember where they are and don’t hit them.
Why do you think the engine is seizing? Because the starter doesn’t work? If so, I would focus on the starter.
If the alternator is bad but the battery is good, the car should start, or at least try.
It sounds like you should do some more diagnosis and thinking about the problem before you start cutting belts and taking the alternator off.
First off, go through it and fix any worn out stuff. May some cosmetic mods if you like, although mostly these are kind of crappy looking to me. There are probably no worthwhile powertrain mods for the in-line six used in the Trailblazer. Cold Air Intakes make a bit of noise but usually no extra power.
When you say “zero” does that mean the low or add line on the dipstick? And it takes 1 quart to raise the level to full? There’s still 4 quarts in the engine when the level is on the add line - not ideal, but enough to prevent rapid major damage.
The important metric is how many miles you can drive before it needs a quart added.
Like-for-like or putting a different engine in?
The metal cap is is on the radiator and maintains pressure in the cooling system. This should be “full the brim” under that cap. The black plastic cap is the overflow bottle. The idea is that when the coolant heats up and expands, it overflows from the radiator into the coolant bottle. When it cools down and contracts, it sucks the coolant back. This does not always work perfectly, however. So check the radiator (metal cap) as well as the coolant bottle. If the radiator is full but the coolant bottle is low, you are safe in the short term. However, if the radiator is low, it doesn’t matter if the coolant bottle is full… you could end up with problems due to not having enough coolant.
You could probably buy 2 reliable cars that are built to have AWD and have that feature for what it would cost to do a shitty and problematic conversion to AWD on a FWD car that was never designed to be AWD (like a 2012 Camry).
Sell the Camry, buy a used Subaru (or other AWD car). Or a new Camry, which is available with AWD.
Or, buy snow tires for the Camry, and an AAA membership in case you get stuck and need a tow.
Has the water pump ever been done? They are plastic, known to leak, coolant gets in the oil, makes a fine mess. You can get metal replacements. It might be a worthwhile “while you are in there” type of thing.
Anything with a fitting that threads into the spark plug hole should be fine. Differences between cylinders matter more than knowing if the numbers are off by a few PSI.
It might be a bit dangerous, depending on how far the battery can move. On many cars, there’s a other things in the way that will stop it from getting very far. However, it isn’t good for the battery to be rattling around, and if it pulls on the battery cables and that causes connection issues all sorts of weird stuff will start to happen, possibly at a very inconvenient time.