Re: spinnaker size
If you want a really easy to use sock, consider getting it one to two feet LESS than your "I" dimension. When you hoist a spinnaker in a sock, you hoist the sock first. If you "I" is 34.5 and you get a 36ft sock you will end up stepping on sock. Also, the socks I've used have the control lines at the bottom.
They're easier to use if you hoist the whole mess and can easily reach down to the bottom and start pulling on the lines. The sail will be a little smaller, but it'll still be the biggest sail on your boat by a huge margin. You can also alter your total sail area by specifying the cut of the spinnaker. There are lots of choices nowadays. Basically the more full it is at the head, the bigger it can be and the better downwind. The less full at the head, the more it looks like a giant nylon genoa and it will be smaller but better for sailing with the wind further forward.
"True, your boat will outperform mine to windward, but my boat will always outperform yours at anchor." --MedSailor