I thought I responded! If not, here goes:
The jib does add some performance, but mainly down wind. It also helps when tacking especially if you have a really raked back mast. It is a small sail and an afterthought at that. I have heard that some people furl the jib upwind when racing because they can point better. I really can't comment on that. The bottom like (and it sounds like I'm contradicting myself) is that it makes is a more enjoyable boat.
To do the conversion, you need to shorten the bridles. Check out:
for length details.
You don't necessarily need the jib block support wires and can mount the jib blocks to the adjuster on the side stays. I wouldn't recommend that, but it is a solution. The blocks attach to the wire through the trampoline and give a pretty good location to control the slot between the sails.
Fuling is a matter of preference. Hobie advertized the Turbo with a furler so you can furl it in heavy winds. Personally, I don't think it is necessary. I have rigged my beach 14s like little 16s and lost the capacity to furl the jib. I have never missed it. I think the real mental hazard is that the stock 14 Turbos used the jibstay as the forestay, so you had to have the jib up all the time. If you furled it, it was protected form wind and UV.
You might be able to get another sail and cut it down, but I haven't heard of a lot of people having luck doing so and I don't think you would save a lot of money after paying someone to reshape the sail. I still have one discounted new jib left.
Hope this helps!