Is the SCSI connector (as I call it) known in the electronics world as a d-sub connector or is that something different?
Not sure, I plan to use DB25 cables, which look like parallel printer ports on the computer. They make DB37 and DB50 cables, which would be a good choice also, but I don't know if these qualify as SCSI.
I plan on wiring the micro switches using solderless crimps. Can the crimp tool used for this also be used for crimping the wires to the SCSI connector?
If I understand your question, it is possible (difficult) to crimp wires to the terminal pins inside the SCSI connector, however, a better solution is to get a fully populated M-F extension cable, cut it in two and leave the wires in the connector in place.
If not, is there a multi-tool available or would I be OK with needle nose pliers for one or both of those tasks? Am I just better off investing in a soldering iron and learning how to solder?
A set of crimping pliers is helpful for the quick disconnects to the buttons, should be under $10.
Is this a sound practice? What would be the advantage of having a wiring block?
Daisy-chaining is actually preferred for the common (ground) wire. However, you probably want a wiring (terminal) block for the main wire to allow easier connections between the buttons and the SCSI cable and to making changes easier if you want the lower right button to be P1B3 instead of P1B4, for example.