Here's a great place to check out various filters and their effects on your image. https://tiffen.com/diffusion/
While in my experience it is harder to get shallow DOF shots with 16mm, it is possible, and I did it fairly often in my recent film (I shot on 16mm Kodak Vision3 film): https://www.youtube.com/watch?v=dLOf-0GoV5E&t=26s
I think that one of the biggest things you can do is to use older lenses, filters (such as Black Diffusion FX, Black Promist, Soft, Glimmerglass, Pearlescent, etc.) and some post-processing (adding some grain in post) to get a film-like look, in addition to the kind of lighting and shots you use.
Something worth trying is the film emulation plugin FilmConvert. I use the Premiere Pro version and it does a good job of emulating various film stocks. One of the things is does when it emulates 16mm is actually lessen the sharpness of the image a good amount, as well as introduce film grain, etc.
That is incorrect. Your shutter speed SHOULD be DOUBLE your frame rate.