Psyvariar: Medium Unit how-to/tips?

I've recently been playing the hell out of the G-Net version of Psyvariar: Medium Unit. The buzz system is completely addictive. I can't stop.

I've been using the ass end of the top 20 player rankings as a goal (previous owners scores I guess) and I can't seem to hit them yet - top PO score is 19,000,000 or so. The highest level is 152 and, since I can't hit these scores yet, I'm just shooting for the highest level I can while getting comfortable with the buzz.

Best score: 11,000,000+
Best level: 106

I understand I need to survive the boss fights in order to keep my buzz chain count and multiply my score, etc., but I'm more interested in some buzzing techniques atm. Some videos I've seen have helped. Here's what I need some pointers/explanations on:

- when to shoot and when not to shoot
- when to spin, which way to spin (u/d or l/r) and what it accomplishes
- best/favorite buzz spots
- what levels to shoot for per stage
- any videos? I think the ones I saw were for Revision...

I'd appreciate any help. Thanks!