Hmm, I am the webmaster for a Sourceforge project so I can give you a little. I don't do much on the dev side though so haven't used CVS or anything like that.
1. Yes, it is free. You get 100MB space for your project and 5MB for your user. These can be increased if you email support and ask really really nicely
2. You get MySQL DBs (not sure how many off the top of my head) but you can't specify users for them. You get three users for your account, one has read-only permission, one has read-write and one has admin. It's enough to work with and that's all you're really after here. You get shell access which in my mind is a big handy feature but the web space certainly has it's share of limitations. Due to them having so many projects and so much traffic, things like suexec would bog the servers down too much so their security is fun to try and work around. The web server can't write to the web space and because they use load-balancing and PHP stores sessions in /tmp you can't use normal sessions out of the box.
Now all those things are workaround-able and if you'd like I can walk you through how as I won my fight with their servers not long ago myself but I'm not going to waste space posting it all here.
3. With a bit of knowledge behind you, pretty easy.
4. Only if you want to, you can just as easily only upload a tarball of your program.
5. Do you mean does the web server have mod_python installed or can you host software you wrote in Python? The former, I don't know for sure but I'm pretty sure no, the latter, of course if it's approved.