ticktock, all your questions have been answered many times before. I apologize that the info you seek does not just jump out at you, this is mainly because people post in the incorrect areas and the forum moderators dont have the power to move posts where they should be. (this should be in the DYI area) Also by viking selling the DYI chip, it is assumed that the installer is knowledgeable enough to figure out the small details like which tacts to use and which programing jacks/methods should be used to best suit the modders needs. Viking encourages the customer to purchase complete modded controllers from the trained staff, which is why there is not alot of support for the DYI chip (we never intended on there to be)
that being said, to answer your questions' any 3.5mm jack can be used, it will come with wiring instructions for the product you buy. (they will all be similar, but different MFG's pins are in different configurations) as for the tact switches, I like to use 7mm switches. 6 mm sit flush with the shell and are very difficult to press. The link you posted in my opinion are too small.