You’ll have a lot better luck here being way more specific. The GL1 was/is a decent run and gun standard def camera, but it does not shoot 16×9 native. So if you want to use 16:9 aspect ratio, I would start with a better modern cam. It uses a 1/8 stereo unbalanced jack so keep that in mind when thinking about mikes.
Documentaries most likely have very different needs than a short artistic film. You need to define what type of shots you are looking to get and a budget. Do you have a crew? Do you want this to look professional or are you just having fun? What is your planned type of distribution and who is your target audience?
Do a search here for lav and for shotgun and you’ll have plenty of answers at specific price points for specific needs. Remember that a shotgun needs a boom pole and a boom pole operator or at least a stand and shotgun holder and boom arm. Wireless Lavs start at $600 a kit which will record only one person at a time.
Do you have a tripod? You can go hand-held but it will be hard to get good results for an enitre film without a tripod.
Mac Pro, macbook pro, Imacs (i7); Camcorders: Panasonic AG-HPX170/AG-HPX250P, Canon HV30/40, Sony Z7U, VX2000, PD170; FCP 6 certified; write professionally for a variety of media; teach video production in L.A.