? about switch for series parallel relays

 so i read the diagram for this and think i understand it. i'll have to put the two relays inside my sub box and wire them up w/ the vc's.  now they need fused 12v which i can easily pull from my power dist block.  and it needs a neg trigger from a switch. what does this mean? i buy like a rocker switch and connect only the neg to the first relay. what about the pos on the switch where does that go? should that run to the power dist block too?  my sub box came which two side terminals so i basically have a spare. can i do this (assuming my first terminal is used for the speaker leads and the sub is already wired to the relays)? run the needed neg trigger to the inside of the 2nd terminal's neg. run the needed fused 12v to the inside of the 2nd terminals pos. then use two banana clips. run one out of subbox neg to the switches neg. run the 2nd banana pos clip to my fused dist block. that still leaves the pos for the switch itself.  i'm looking at a 5v switch w/ 3v led. should u run this pos to another opening on my power block. it has 4 8gauge outs. 2 will be used, leaving 2 left for misc stuff. or can i share one of the 2 open slots. i wouldnt be using 8 gauge, likely 16-18 gauge running 2 pos's out of the same out, one to switch and the other to the banana clip.  originally i thought of drilling a small hole in the subbox for the switch but i'd still have to get a pos wire inside so it would be pointless. i have the unused 2nd terminal on the box. might as well make use of it.  oh i'm adding a stinger long fan to flow air across my amp rack so that'll need power from my dist block too.  if i stick the switch's pos, fan's pos, and the relays pos into the 3rd opening of the dist block, i should use an agu fuse totaling the amperage of all three for that slot and then the inline maxifuses on each of the 3 lines after the block. does this sound right?  i tend to be thorough and might make this sound more confusing than it is but i can picture everything in my head, its harder to put it into words.

side question, cuz i'm also going to use a relay for the remote turnon for 2 amps and the fan.  what method do u guys use for multi items on the same line as far as connections,  do i run these 3 lines to the relay, twist the ends and crimp it onto one female spade?   how about the wiring for the subs. how am i going to crosswire two voicecoils w/ 10 gauge twisted wire. should i pull the twisted wiring apart to make it easier. use t taps?