I'll echo some of what's already been said...
My recommendation for starting out is use some existing templates (google "Doc's Lures" for a free video tutorial and free templates), and after using existing material to get familiar with the design and building principles start branching out. Go nuts, see what works, let us know. I've trashed several designs, but the nice thing is the failures make either good kindling or good Christmas ornaments.
1) Seems like most lures are shaped to match or generally mimic the local forage...maybe with the exception of topwaters, there's a lot of variety there.
2) I use whatever wood I can find, often scraps. Luckily, I've been able to resaw much of it on a bandsaw, so I typically cut the wood to 3/4 or 1/2, and I'll just use whatever looks "right."
3) I've done all mine from 1 piece so far. Lots of folks use multiple pieces, especially those who do 3D printing.
4) I've used twist eyes more than through wires, and I've use a figure 8 through wire as well as a bent single piece of wire. So far I haven't had any lures fail, and I've caught most of my fish (bass) this year on a 2 1/2" popper with twist eyes.
5) I've nothing to add here.
6) Look up Doc Lures, he's got a good free basic class. I got a lot of good information there.
7) Have fun and go nuts. I've only been doing this for about a year and a half, but this season I've caught a majority of my fish on lures I made, which is a TON of fun. I've even been able to sell a few lures, which is a nice bonus. Ask a lot of questions and utilize the search feature frequently. There's a lot of insight on here, and the more experienced folks seem to be happy to help.