The Dynavin has simple audio controls, similar to stock. You dont NEED a processor but if you WANT more adjustability, EQ, time alignment, active crossovers, etc... by all means run a processor. Ive run processors or EQs in my personal cars....well...always. I currently run a JBL MS-8....similar (kind of) to the Audison Bit One you mentioned. The EQS would be a decent way to go for adding EQ and bumping up the voltage. If you know what you are doing and you have a good ear, a processor is an awesome way to go.
Crossover point is going to be totally dependent on the speaker set you are using.....I dont know where those speakers crossover but most components crossover between mids and tweeters in the 3K range. If it were me though....id probably just use the crossovers that came with the speaker set, Boston knows what they are doing....
Just like everyone else, I fought to get any midbass in the door of my E46 with little success until I cut the door behind the speaker....make a nice baffle, cut the panel, and save yourself the time of having to do it over.