File ownership

Having a slight problem with the file ownership and permissions.

I have no administrative access to server WP is running on, just a regular user account on a linux server.

We have been hacked a few times and malicious code has been uploaded but they have not been able to edit the pages so for the most part it has gone unoticed by our visitors.

Now for the problem(s).

1. In wp-content/uploads all uploaded files are owned by nobody:nobody and have permission 666 (777 for folders). How can I as an ordinary user take ownership and/or change permission?

2. What are your update routine for keeping the site safe? Should I always use the shell and do it manually or is there a safe way to do it in wp-admin. I rather not let the site be writable by the web server.
If I get an answer to question 1 I was thinking in the lines of making a small script that makes the site writable by the web server, do the update in the gui, then run another script to tighten permissions again.