A: NO, Your site will not automatically get a penalty.
My Thoughts: It may trigger Google to take a deeper look at your site and make sure there are not lots more sites like this. If you are aware of some links like this it would not hurt you to put them in the disavow file.
A: If you are aware of a large number of links that are unnatural then it could be a good idea. Otherwise NO
My Thoughts: Plenty of sites are still getting penalties every day, so prevention unfortuantly looks like the best way forward.
A: NO, the meta data is only shown in image search as extra information, you cannot stuff keywords in to the meta data for ranking purposes.
My Thoughts: How you name your image is important and I do wonder if in the future Google will start to use EXIF and XMP date. However it could be easily abused as well.
A: Yes it is a Manual Penalty, However Google does not believe it was your site that is at fault, so there is a manual action to ignore those links specifically. John suggests that you figure out what the cause was as a preventative measure.
My Thoughts: It is a Manual Penalty and Should be dealt with, it could be one of you major traffic pages. I do think Google should let you know what page is effected.
A: Maybe, Jogn says No but later suggest that if links are bad and you think the links might be changed to DoFollow at some point then you could list them.
My Thoughts: You are not going to get into trouble for listing NoFollow links in the disavow file.
A: Yes, if they are not great links, just disavow them and move on and get out of the Manual Penalty as quick as possible.
My Thoughts: It can always be removed from teh disavow file at a later date if it really important.
A: It is OK, but it is best to have a file in Google Docs to show the work you have done to clean up your links.
My Thoughts: Creating a spreadsheet of all the links and details of how you have tried to get links removed is the best way to go, especially if most of your links are bad.
A: NO, John says view the source of the page or use any tool as they should all work.
My Thoughts: I think it is irresponsible of Google to expect webmasters to find dofollow links without recommending a tool.