NAWY2J ... this really is a helpful forum of people, but you need to demonstrate that you're trying to find the answers yourself. Instead of asking basic questions, tell us what you found in your research and then tell us what you want to clarify or double check.
Now for some basic help ...
Do you know your scale length? That will help determine the bridge placement. Take your neck and measure from the bridge side of the nut to the 12th fret and double it ... you'll probably come up with 25.5", or maybe 24.75". So the point at which your strings break on your bridge will probably need to be 25.5" back from your nut. But got to the Stewmac site and enter your frets and scale length and it will give you the specific / accurate measurements for your bridge.
Stewmac Fret Calculator
As for the tailpiece, you've got a bit of flexibility there. It'll be about 1.5" further back from the bridge but take a look in a guitar store at one you like. Also when you are doing that, note the slight angling of the bridge.
As for earthing your electronics ... if your using a T-O-M bridge, carefully drill a hole from you electronics cavity through to where one of the TOM posts will go into the body ... you'll probably need an aircraft drill to do that. Feed your earth wire through and (preferably) solder it to one of the posts before you tap it into the body. But go back to the Stewmac site for wiring diagrams which will show you all your earthing (and other) points. Basically though, you need to drill connecting holes through each of the cavities and jack outlet.
Stewmac Wiring Diagrams
I think it would help if you post a few pictures as well so that we can all see how you're progressing.