Is it worth replacing the luff tube on a sail, or is that repair too major?

Also,when I last purchased a sail (7.5m) the thinking was that sails should be relatively short with a long boom. I don't like that sail much it seems unwieldy especially if the wind is light enough to use it.

What is the current thinking on sail height versus boom length?

I am an intermediate sailor sailing a Bic Nova. Typically I use a 6.5m sail in 15 knots (the one that requires repair) but I have a 5.5m Gastra with a single camber (purchased second hand over 10 years ago). The Gastra sail is so much easier to sail with. It just feels right.

What is the current thinking on cambers?