Do your soffits first, if they are not done. Then the corners, J-Channel around all the other openings, Starter piece at the bottom.
Nail every 12-16" but NOT too tight, just snug, so it can expand and contract with weather changes. Overlap about 2-3", but make sure the Overlap is away from you when looking at the siding, looks cleaner and you won't see the seams as much. so you may have to start from the opposite side to get it to look correct.
Most of the newer vinyls shouldn't fade too much, but make sure it's a brand name and a standard Size (Double 4, Double 5, beveled, etc...) and a standard color so if you have get replacements in the future, you can.
Yes, turn your circular saw (fine tooth blade) and put it on backwards, it cuts thru it pretty slick. I have also used a sharp pair of metal snips/cutters .
I am actually doing clabboard (Wood) siding on my garage to match my old house. Triming is a pain, but looks so good when done.! Good luck.
Some really good info/pics!!http://justwoodandnails.com/exterior/in ... -facia.htmhttp://justwoodandnails.com/exterior/j-channel.htmhttp://justwoodandnails.com/exterior/ov ... siding.htm