zehrila - 9:24 am on Jun 23, 2013 (gmt 0)
1: If it is on spammy or irrelevant site, contains rich anchor text, it should be in your disavow list.
2: If it is in Google's index and it does show in your backlink profile, best bet would be to add it in your disavow.
3: Check if that particular page ranks for its keywords.
4: Those links are often nofollowed, adding them in disavow won't hurt !
5: No, if it is related and is on quality site, there is no point in disavowing it. A lot of .edu and .gov sites have such pages with hundreds of useful links with in.
6: Should be highly relevant and must not use rich anchor text to link to you, should use your domain name as anchor text! Better not be doing link exchange though.
7: I would say do it once, but be very careful with selection of sites in your list.