Lots of flies are tied on size 12 hooks. but a size 10 is good too. As has been said a lot depends on the size of the trout too. Here in Vermont small streams a 6" brookie is a nice fish, while the bigger rivers and ponds can hold really large ones.
I wouldn't be without them. I've made the frames since I started bending wire. Hagen's sells the frames with and without blades and swivels, but as far as selling IMO there are just way to many out there to make any money on them.
Been pouring them for years and yes use crane swivels and yeah I know they've gotten really expensive but they work so much better (thankfully I stocked up years ago)!! I use german split rings from Hagen's and they're not that expensive by the 1000. Just make sure you keep them separate from your good ones!! LOL
Well there is no such place! As I also tie flies I've built up quite a mass of materials. I get some nice skins on ebay. Check with goodwill I've found some nice old beat up fur coats for cheap - tear out the lining and you can cut them into zonker strips! or cut the fur off and use it that way. The feathers from craft stores I've never seen any good in them and folks I know who've tried the boa's the color wash's out. Enjoy the madness!!
I use these, their surgical towel holders you can get on the bay. A member on a panfish board recommended them for breaking powder paint out of the eyes and they work great.
I made mine from instructions that Cadman sent me. A buddy on another board sent me some filter material but I haven't been able to match it at McMaster Car to buy more.