OK. So I'll get some tell tales. Do they go in very specific places on the sails? A good book seems a good idea too.

Regarding the rig, this time I tensioned it pretty hard, following Bert's advice. I rig the boat by myself (my crew is a bit young) so I wasn't quite confident on using the mainsheet with the main up to release tension on one shroud. Instead, before hoisting the main, I took the mainsheet system out of the traveller and attached it with a short line to a rudder pin. Then used the mainsheet to tension a trap wire of the same side. It was pretty effective. First I tried something similar but tensioning the jib halyard but it didn't work nearly as well. But I'm a bit afraid I might have got a bit too far. When I hoisted the main and tensioned the downhaul I noticed that the upper part of the mast curved to one side. I tensioned the opposite diamond wire to straighten the mast (side to side) but the tip of the mast still curves to the side when I rotate the mast (it happens evenly to both sides). The wind seems to compensate that and keep the mast in column, but maybe it's not the way it's supposed to be done. I wonder if I'mm applying too much rig tension or too much diamong wire tension. I hear talking about pre-bending the mast with the diamond wires, which wasn't happening yet. (And I'm not sure if it's the right thing to do, it seems to take lot of tension). I also noticed the mast was quite harder to rotate, so I am guessing I can go back a little bit on the rig tension. Quite confusing for me, so any advice is wellcome, including a good book or a specific tuning guide for this boat, I haven't found one yet.
Thanks again.
Andrés