If you don't have a lathe, probably the easiest way to taper a wood mast is to chuck it up in an electric drill. The drill needs to be clamped to your work surface somehow (vise, c-clamps, or whatever) and run at a relatively slow speed. Fold a sheet of sandpaper several times into a fairly thick pad (otherwise the heat will burn your fingers) and hold it up against the spinning wood. Start with fairly coarse sandpaper to establish the taper, then work your way down to extra-fine. It may take a little practice, but you can make perfectly satisfactory spars that way.
The choice of size and scale needs to be a matter of personal taste and skill. The three-foot size you've mentioned is on the large side of medium. A good-sized ship reduced to that size typically will be on the scale of 1/8"=1'. That's a good, medium scale that's comfortable for lots of people. Smaller vessels can conveniently be modeled on larger scales; if your eyesight is such that you have trouble dealing with dimensions under 1/32" you might consider a larger scale. Other modelers like smaller scales. Some people work best with their fingers, others work best with their wrists, and still others with their elbows. One of the first things a serious ship modeler needs to do is figure out what scale suits him or her best.
There are two good wood
Constitution kits available. Both are a bit bigger than three feet, but they're excellent kits. The big difference between them is the hull construction method. The Bluejacket one has a solid, carved hull; the Model Shipways version is plank-on-bulkhead. Your choice between them probably should be based on which construction method you like better.
There are so many wood H.M.S.
Victory kits on the market that I've lost count. On the basis of the photos and reviews I've seen I can only recommend one of them: the one from CalderCraft (otherwise known as Jotika). I haven't bought it (nor am I likely to; it costs about $1,000) or seen it in person, but by all accounts it's an outstanding product. I haven't bought any of the other wood
Victory kits either, but they're made by those Continental companies I mentioned in my earlier post - the ones who don't seem to understand what scale modeling is. I would suggest avoiding those kits like the plague. They're cheaper than the Calder/Jotika one, but still well up in the hundreds of dollars; the extra money for the better product, if you can handle the initial outlay, would be well worth it.
I can't resist seizing on one phrase from Old_McDonald's last post, in which he said he'd built the Heller
Victory but "just can't paint it to look like a wood kit." In the first place, in terms of scale accuracy the Heller kit is far, far superior to any of the wood ones except the Calder/Jotika one. In the second place, if scale modeling is your interest, give some thought to what the objective of the hobby is. I personally have no desire whatever to make models that look like wood kits. I want them to look like ships. There's a difference. If I built a Heller
Victory and somebody said "oooohhh, it looks just like a Mamoli one!" I'd be profoundly insulted.