The drying time will vary - it depends on how thick the slab is and the current weather conditions.
If you go with metal poles, nails probably won't be an effective fastener. You could drill a hole in the pole and use a nut and bolt. I prefer screws/bolts over nails even with wood. With screws you can take it apart easily if you need to replace a component. Nails aren't designed for this and will usually cause some damage to the wood if you have to pull it out.
I've never done any metal-pole construction, but I suspect that metal clamps and brackets might work better for some purposes. A walk through a large hardware store like Home Depot will give you a good idea of what's available.
This aviary-building guide tells you to solder the wire to metal poles:
http://www.ehow.com/how_8735526_build-o ... rrots.html That's a good idea, although I think I'd want the soldered part to be on the outside of the aviary, not the inside part where the birds might chew it.