Temporary Wiring

I've just purchased all new equipment for a starter (HO) layout,
including a Digitrax Zephr DCC set. I haven't done the benchwork
yet and would like to test the engines and familiarize myself with
DCC programming, just using the dining room table .
What's the best way to *temporarily* attach wires from the DCC set
to a section of track (in other words, without soldering)?

Speaking of wiring--at the train store I mentioned I wanted
12 gauge wire for my bus lines, which is what seems to be
recommended everywhere I read. The "regulars" hanging out at
the store all muttered that 12 was way too much for a 4X8 layout
and said I should use 16-18. Agree or disagree?

eagle37