I'm actually surprised that whatever system you're using has you upload the letters yourself. Typically (maybe this is field specific?) an applicant should not even get to look at the letters, since any negative (or neutral) comments the writer includes might strain their relationship, and so excluding the applicant means the writer can, in theory, be more direct and honest.
1) This is bad. A generic letter is obviously better than no letter at all (if one or more is required), but not always by much. It indicates that you are interested in a position somewhere rather than interested in a position there. If your other qualifications are superb this might not matter, but you can give any application a really significant boost by showing the people who will be reading it that you are interested in them and will be a good fit. This doesn't mean totally different letters for each application, but you will have to help your letter writers to tailor small changes, for each letter, that "personalize" your applications.
2) This is probably bad too; if they didn't request letters, then they don't want them. At best they'll ignore them, at worst they'll be annoyed that you don't follow directions.