It looks like the bullet repulsion of the last evolution knocks away any bullets that you graze, as well as any bullets in a certain area when it activates. Any bullets coming head-on, or you move too fast towards, will not be repelled.
But of course, once you get Counter, that's not much of a problem.
I'm very partial to the Chain bomb, since it comes into great effect in the last stage. Summon is similarly hilarious.
The Stage 4 Green DNA appears to be held by a red (actually magenta, enemies in this stage seem to have a color change if they have an item) hexagon after the tunnel section. Spawn point is on the FAR right side. High chance to miss it altogether, if you're getting a large amount of orbs - it's way too easy to hit 800 right before it spawns. Not only that, but it's almost always offscreen, if you're staying near the middle of the area.
Also, try doing a replay - it looks like fast-forwarding at all will cause desync.