Silver (not the silver plated stuff) is sold by levels of purity. The entry level purity for audiophile purposes is "4- nine". This means the silver is 99.99% pure (or four nines). Do not cheap out and go for 3 nines, or some silver plated crap uless you are wiring the inside of something. For cables and I/C's- 4 nine is the bare minimum required for best sound. Sometimes, 5 nine silver can be had for a decent price, and that is even better (if you can afford it).
Silver is drawn into wire by standardized weights. Thus, it is hard to get a large guage wire in a long length. A 28awg wire should be easy to get in long lengths, but don't think buying more means saving money. The price of silver is just like gold- strict by weight .
Silver seems to benefit from a heavy cotton dialectric when put in the open air. The internal parts of electronic components seem to favor teflon dialectrics. This is just one of its unique properties.
The use of silver cables has a mixed reaction, and this is due to all the really bad (cheap) stuff saturating the market. When you spend the money on the good stuff (4 nine minimum), and honor it's requirements (cotton dialectric is ideal in open areas), you'll be rewarded with a wonderful cable.
I don't think braiding will yield much "sonic" benefit with pure silver. If you are going with a balanced connection, it may be easier to just braid it (for neatness). I'd go with an extra, and braid in a loose Litz. Most of what I have read (and in my brief experiences) suggests silver does best with a loose twist- if anything at all. I have very low RFI in my environment. You may have to experiment with that one....
Also, remember to take a piece of steel wool (0000) and run it lightly along the entire length of wire before putting it into any kind of dialectric. This will remove any potential "haze" on the wire from dies or oxidation. I also suggest a very light misting of Caig's preservative. When silver oxidizes- it remains just as conductive (it's still silver), but the tonal qualities shift ever so slightly.