If I had DOS then I could have installed an old version of cygwin and then got my favourite GNU tools working! Jobs would have had a fit it I could have done that.
Even worse, you could have run loadlin and run an old distro on your phone. Play with it a bit and I'm sure someone would have found another way of getting Android up and running on it.
1. Depending on where you are in the world, yes or no. In NZ, yes, you can use whatever network you wish
2. I didn't know Skype wasn't allowed! I have Skype on my non-jailbroken phone. I picked it up on the App Store for free. To get to your point though, no, you cannot use the other app stores around which is a serious shame
3. I play MP3s all the time. No DRM.
If it is a 3G or a 3GS at firmware 3.1.2 then yes, you can jailbreak pretty damn easily. You can just as easily put it back in jail if you like.
The optimum committee has no members. -- Norman Augustine