Can I redeem delta skymiles for a ticket on Continental, NWA or another airline for domestic or international tickets?

Yes, you can redeem miles for travel on any airline that is part of their alliance. Continental, NWA, AF, among many others, are all part of it. Check the Delta website about which airlines you can travel on vs just earn miles on. You do have to go through Delta to book the flights though.

Yes, just call Delta and follow the prompts to the partner award desk. When you call Delta, if you get that awful, newly implemented voice non-recognition system, remember that you can also key your choices. The keys correspond to the order in which the choices are given. For example, if it says 'please answer yes or no', you can press 1 for yes or 2 for no. You get the idea. This keeps you from having to repeatedly scream 'RESERVATIONS!' 15 times and helps to maintain your sanity

It took me several frustrating days to figure that out.

Here's the award chart for travel on Skyteam airlines (Delta, AeroMexico, Air France, Alaska Airlines*, Alitalia, Avianca*, Continental Airlines, CSA Czech Airlines, KLM Royal Dutch Airlines, Korean Air, and Northwest Airlines)
originating from the continental US, Alaska, and Canada:

http://www.delta.com/skymiles/use/sk...t_us/index.jsp

Here's the award chart for non-Skyteam partner airlines:

http://www.delta.com/skymiles/use/pa...ards/index.jsp

With Skyteam awards you can mix and match multiple carriers on one ticket. With non-Skyteam partner awards, you're limited to flights operated by that partner only on a single ticket (with the exception of using Delta operated flight to get to that carrier's US gateway).

*While Alaska and Avianca are not Skyteam carriers, they've been grouped into the same award chart. I would assume this to mean that flights on these two carriers are also eligible for multi airline ticketing.

Plan to stay on hold for over an hour. I did. But I got my flight. I was hoping for Air France but it and most are with Delta and Continental.

I've called the partner award desk half a dozen times in the past week and my average hold has been about 2 minutes