Sorry if someone else has posted something similar elsewhere or if you feel this should go in an already existing thread but get over it dork.
So for the last fight where you have to protect the generator you might find it a little tough on 1999 mode but Those Days Are Over Chum.
Equip the 'Return to Sender' vigor, hold down the trigger and throw a bunch of shields around all sides of the generator, if you get a good amount of coverage any and all bullets fired at the generator will be absorbed into the shields and you wont have to worry about a thing. Rockets can still hit it but they do so little damage that you can take your time dealing with them.
From there feel free to deal with the rest of the dudes however you wish, personally I just had Songbird take out the dudes on the deck whilst I rode around boarding the zeppelins and generally being a menace. The patriots will keep appearing indefinitely but son you got an invinci-generator. I think that covers everything?