**1. Train traveling at 50 mph needs X amount of distance to come to a complete stop. ****1 mile? 1/2 mile? 2 miles? (not an emergency stop). **
This is going to vary widely from place to place, train to train. A load of empties will require more distance than the same amount of loads to come to a full stop. Likewise, wet rail will impact stopping distance, as will grade. Length of the train affects not only the train’s mass, but adds distance to the brake pipe (the pneumatic brake release initiates from the head end and takes time to propagate to the last car.) Passenger trains can go from 79 to an emergency stop pretty fast. The train you’re talking about would probably only take a few hundred feet to stop.
2. If the couplers for passenger trains are the same as freight and if they can be joined together creating a mixed type of train.
Yes, they can be joined together. Amtrak’s Auto Train runs with both passenger cars and auto carriers at the end (they could be reversed if Amtrak wanted to spend the money to install electrical cables on the auto racks, but that’s an expensive solution to a non-problem, really.)
Passenger cars nowadays have “lock tight” shelf couplers that are designed to not break apart in an accident or on rough track (mainly, this means there’s a shelf preventing the knuckles from sliding vertically and disconnecting.) There are different “grades” of couplers, but they’re compatible with each other.
**3. What is the least amount of obstruction on the track (besides warped or missing rails) that could derail a train, i.e. log or a deer’s body or even a human/zombie body. **
Bodies wouldn’t do it. 99% of the time, in a grade crossing accident with a car, the automobile is destroyed while the train stays on the rails, usually without a dent. Warped rail in warmer areas (due to “sun kinks”) is likely to cause a derailment, as is a washout of ballast under the track, a number of rotted ties or missing spikes, etc. One could probably fashion a portable derailer out of a hunk of metal, but all things considered it’s pretty tough to derail a train.
4. minimum number of crew to operate the train, including engine and cars.
One. Engineer’s all that is needed. On Amtrak runs shorter than 6-8 hours, there’s only one man in the cab. Your average freight train operates with a crew of 2–engineer on the throttle and conductor filling out paperwork.
5. Is there a fuel car that could feed the main engine enroute? Or does the engine need to stop to refuel at designated stops? **
You can fuel the locomotive from a semi truck tanker, a designated stop, or possibly a railroad tank car full of diesel, if you had the hoses. Locomotives have a fuel cap just like cars…it’s not a very complex process. Bear in mind, though, that with several thousand gallons of diesel in the tanks, a locomotive can travel cross-country without refueling.
6. Distance a train can travel on full fuel tanks without stopping? **
Coast to coast.
**7. Proper name for the truck that drives on the rails with those special wheels in front and back (this will be used by the train survivors to “drive ahead of the main engine” looking for obstructions or damaged track" and warn the engine (via 2 way radio) to stop. **
Vis-a-vis the caboose: you’d probably find a few in any division rail yard. They’re not used for their original purpose (the conductor has been moved to the locomotive because of the Flashing Rear End Device) but will often be tacked to the end of local trains that must do a lot of movement in reverse. The railroads just use old cabooses for that purpose, though they dub them “shoving platforms.” The idea is that a crew member will ride the caboose and radio the engineer about the track ahead.