In theory, yes. The engine will power the truck perfectly well.
However, engines have mount points, places where the engine is secured to the truck. Most likely, the 8-cyl will not fit the mounts where the 6-cyl once was; it's just a bigger engine. You could get very lucky and have them match, but it's not likely. Your best bet is another 6-cylinder engine from another nearly identical car (i.e., the year is only different by one or two). Websites exist that will tell you the engine number and which ones are compatible with each other. It is also possible to buy adapters to bolt a suspension from a Ford onto a Chevy frame and engine, but that doesn't sound like what you're asking.
Yes you can.
The cylinder heads are diffrent. Intake from 1998 truck will not bolt up to 1990 heads.
it may have a used engine from a 95 truck put in it. Or, it could be a late 1994, and Toyota was installing 1995 starters on the last of the production run for that year.
You have to install the master cylinder that is compatible with your truck otherwise if will not work. There is really no difference in a 2wd & 4wd when it comes to the master cylinder.
With engine oil filter change the 4.2 liter V6 engine in a Ford F-150 takes : ( 6 quarts / almost 5.7 liters of engine oil )
yes
yes
None
With some modification, yes
yes
With money and fabrication you can do most anything.
no...... you tear the engine up