Bill, do a search on "strings", or "endless vs. flemish", etc.--there's been plenty of discussions and lot of opinions offered. After that, if you have any questions just post them.
For serving, I like 62XS--very tough, comes in several sizes, doesn't slip easily. Halo is very tough, but is more prone to slip, especially on small diamter strings. I had problems with the outer sheath of Diomandback breaking loose when I tied off my serving. Nylon works ok, but only one size and isn't too durable. When monofilament serving breaks, it's over--and you have to be watching close to get an idea of when it might break.
Chad