Hi Ramon,
This is a very difficult question to answer. Before I even try to answer it I'd like to point out the following:
The first Panda filter came out on Feb 25, 2011. On Feb 24, 2012 Search Engine Round Table published a survey asking how many webmasters recovered from the filter one year later. The survey can be found here. As you can see, not many were able to recover from the filter even one year later. This is by no means a conclusive study, but it's really the best we have.
To answer your questions:
1. In my opinion, it's beyond fixing if you lose rankings and you did NOT receive a warning from Google. If you received a warning consider yourself lucky. Follow Google's instructions and use a service like linkdelete.com to get the bad backlinks removed (or just do it yourself).
2. Open Site Explorer works great for identifying bad backlinks. Go through the list of exact match keyword anchor texts and you'll be off to a good start.
Finally, I'd like to plug my post on this subject:
How-To Recover From Google Penalties & Filters
It's a long one, but I include several pictures and examples to make this process easier for folks in your situation.
Good luck!