Not much I can add, but here it goes.

1.) Do you unstring it or not? How often and Why?

Sometimes, mainly for convenience sake. I wouldn't travel with a strung recurve, because if it got hit just right it could knock the string off and damage a limb.

2.) Why can't you use certain strings on an older bow? Like the Dyna Flight 97 or whatever it is called? Isn't a string a string?

B-50/B-500 is polyester, or Dacron. It has much more stretch than the modern materials, such as Dynaflight '97 (Dyneema '75) or 450+ (Dyneema and Vectran). To give you an idea, have someone "saw" your finger with a piece of yarn, then with a piece of monofilament fishing line--get the picture? The new materials are harder/tougher, and can damage the limb tips if: (1) they are not reinforced with micarta, phenolic, etc. and (2) the string grooves have to be cut at a different angle. I have seen two old bow that had the limb tips literally sawn off by a Fast Flight string.

3.) What is the difference between 3 and 4 feathers? What about broadheads? Will it affect the arrows flight if you use a wrong combination of head and feather?

None that I can see--4" 4 fletch flew the same for me as 5" 3 fletch. Some folks have talked about certain heads not flying true for them, I've never had that problem. Perfect arrow flight is a must for hunting though--both for accuracy and penetration.

4.) Do you pratice with broadheads or use field tips? If you use field tips how do you get the weight up to 8 grains/lb?

Both--field points most of the time, but broadheads before hunting season. You can buy field points in different weights to match your broadheads.

5.) And tell me EVERYTHING!!

No can do--some things you just have to figure out for yourself. The main reason is what works great for you may not work at all for me, and vice-versa. Remember there is no one perfect shooting style for everyone, as there is no one bow that is perfect for everyone. Don't be afraid to experiment and take notes. As was already noted, consistency is the key. It's a constant learning process.

Lastly, keep in mind there is no magic bow. Shooting different bows is part of the fun, and swapping up if you can afford it, but finding a bow that fits you and sticking with it is what will make you a better shooter. By the one that fits you, I mean one that fits your hand properly, is comfortable, made for your draw length, etc.

Good luck!

Chad