srsly though, ND filter, just get whatever you need for your largest lens and step it down/up if necessary. i have a 77MM that i use on all my stuff, which happens to all be 77mm threaded save my 35L, where i use a 77 >72 step down.
sounds like you have everything to start making a movie, so get out and shoot
if you dont already have good audio gear....good sound is more important that good video
a field recorder like the H1, H2 or the H4n is perfect, don't necessarily need a boom until later, just get some cheap lavs or turn down the levels on the H1/2/4 so it doesnt pick up too much.
i use pluraleyes in Premiere to sync all my clips/audio automagically.
