I really havn't started messing with sound files yet but a possible idea for:hmm: #2-the air-raid warning:
Maybe try to merge your "siren" file in with the AA guns firing file (if there is such a thing). That way when the harbor guns start to open up--the siren will kick in.
Don't know if that will work but maybe one of the guys here who have been tweaking the sound files for awhile will be able to help you with a solution.
ps: if you get it working please post your fix or make it available