I've done a fair amount of development work. A lot of what I've done is self-taught. I also hire people on a freelance basis to help with discrete tasks.
Partnering with someone is really taking it to another level. You need to know the person well and really trust them.
I haven't really done much of this, but I've hired employees and had my fair share of problems with them. It is something you need to be very careful with. I did partner with someone on two different projects, and the partnership worked well, but the business model didn't :-(
Of course, if you can get partnerships to work, it should pay off nicely. I know people who have done this, and most of their contacts for partners are made at industry conferences.
It probably is also worth getting a good grasp of everything that's involved, even if you're not doing it yourself. SEOBook.com is a good place to start for that.