you talking about block connectors or board connectors?

I use a utility knife. Nothing special.

I personally have no experience with the value series housings, as I usually bought most of my stock of connectors from Mouser years ago before I really knew much about GPE. I'm sure for 99% of applications, the value series will be just fine. Might want to stick with the OEM Molex stuff for high temperature areas, like GI connectors though.

Good question. I usually just stock up on all sorts of various sizes, but yea, you can't go wrong with the largest size you can get. I usually stock up on smaller sizes too, just so I don't have to cut and slice up so many different connectors.

While you're buying things, go for trifurcon branded female connectors. They have little "wings" that hug the sides male end of connector. They're especially good for GI wiring, as it maximizes metal to metal surface area and reduces resistance and heat which plague these games.