The truth of the matter is any good quality twisted pair shielded 22awg cable will do perfect for in wall microphone cabling. I personally prefer the foil shelded with drain wire type.
What will matter most is the XLR brand of connectors you use. I use nothing other than Neutrik connector. There are many brands that have copied their design, but none come close to the quality. Not even the old faithful Switchcraft line.
The final piece of the puzzle is how you assembly the connectors. Be sure to put some insulation tubing over the shield/drain wire to keep it from creating ground loops where you don't want them.
As to speaker wire, I have always just used 14 or 12 awg twisted pair non-shielded and again any good quality cable will do the job. If I'm running cable for a constant current system, I'll use 16 or 18 awg twisted pair non-shielded. Yes you can use smaller, but your really taking a chance of major signal drop and blown speakers or a fried amp.
Do not use any type of cable that looks like zip cord. If you do, your just asking for noise to be picked up by it. Save it for you home speakers if you must use it.
