Each time you go back and do another level of NCRC, I guarantee you will reevaluate your options and end up buying even more gear. Welcome to the club.
The answer to your Prusik question is approximately 18 inches, AFTER being tied in a loop and measured tight end-to-end (between 2 points). So you'll need to start with a minimum total length of 36 inches plus the Double Fishermans bend plus short tails. Snoboy's 135cm length sounds about right. This should allow you to tie a 3-wrap Prusik to fit snug under a 2-inch PMP, but you might want to go a little longer for larger PMPs or a little shorter for smaller ones. A flexible 8mm cord is recommended for Prusiks on 11mm rope, but 7mm should work OK for what you need. Best plan is to get your PMP and rope and Prusik cord together, and tie, test and adjust the Prusik before cutting it to length.
For the mine application you described, are you talking about pre-rigging a 3:1 haul system using your main rappel rope, or piggybacking a 3:1 onto the rope later if you need it? Either way, lifting 1 person plus the weight of the rope plus edge protection and/or redirect pulley friction will require a lot of work from at least 4-5 people. Or you could go with what Scott suggested and pre-rig a piggyback 4:1/ 5:1 jigger with a pair of 1 inch twin sheave pulleys using 7mm or 8mm cord. Less force and people required to operate, but this will take longer to haul and more resets. Keep your jigger kit in reserve for if you need it, or carry the components spread between several people on a trip. Or pay the big money and get yourself a
tiny commercial jigger system.
An alternate option at the top of the shaft is to use a counterbalance system, especially if your help is limited. Let your body weight and/or climbing efforts do the work, providing you have enough equipment and expertise to manage it. But that's a whole other can o' worms. If you do stick with a haul system, consider using a Pro/Mini/Micro Traxion for the PCD in place of a PMP and Prusik. The advantage with the Traxions is that an integral cam is much easier to tension and release and generally adds less friction than a Prusik in this configuration. Just be aware that the rope feeding through any device with a toothed cam should not be allowed to sustain a shock load or there could be disastrous consequences!
I also agree with Greg about the rescucender - probably not the best value for money in your application. However I also think certain mechanical cams have a definite advantage in handling and efficiency over a 3-wrap Prusik hitch for applications like a haul cam. Have you considered the
Microcender instead of the Rescucender? Similar design and performance, but about half the size and slightly cheaper. I have several of each, but I keep the smaller ones on my pre-rigged kits because they are just a little more compact.
Have fun with your rescue pre-plan!