Rick White's book is a good one to get started on these things. I'm sure it's available in the on this site...I think I got mine from Amazon some time ago.

Don't get crazy over rig tension. It doesn't really add that much to the boat performance. The leeward shroud is ALWAYS going to be slack when trapezed and too much tension makes mast rotation difficult (really important to have good rotation on a boomless boat). Downhaul, wind pressure, trapeze weight, etc. all make the mast bend which makes it shorter. The boat flexes too. Rig tensions is the last thing I worry about. I usually hold on to the trap wire off the rear beam and let my crew pin/screw the shroud down at that point - and don't worry about it any more. Diamond wire tension is 20X more important that rig tension.

There are a lot of different ways to set your ideal diamond wire tension...some will advise to lay the boat over on it's side and hoist the main to the top of the mast (pinned at the bottom with the downhaul) without the luff in the groove. Adjust the mast prebend to the shape of the luff. I'm not sure how all that works so I usually go by the tuning guides for my boat and use a wire tension gauge. Diamond wire tension really makes a big difference in the light air speed. In heavy air, correct tension reduces how big the adjustments need to be to respond to puffs...and it does help the boat respond to gusts a little more automatically. (Where legal), I sometimes adjust diamond wire tension between races.

Diamond wires can carry a LOT of tension - up to 800 lbs of tension on each wire in some cases. Depends on the boat/mast, geometrical arrangement, and what the system can withstand.

During this year's Steeplechase, I forgot to address our diamond wire tension that was left on a moderate-light air setting from my last regatta. I noticed on the long upwind 2nd day that our windward diamond wire was getting slightly slack when depowering in the times we had extended pressure and gusts (HARD on the downhaul and mainsheet). We were plenty fast...and it probably gave us a little edge when the pressure was down - but I should have had it a little tighter to make the boat a little more manageable while in the pressure.

On my A-cat - diamond wire tension makes a gigantic difference in the boat speed from 8 to 12 knots of breeze. One day I'll get some time to make a live adjustable diamond wire setup on it.

I like my jib tales about 1/3 down the luff from the head about about 20 - 25% up from the tack.