1. It doesn't overclock anything, you need sys-clk to OC
2. Partially, because Docked uses also some higher quality settings + some type of AA
3. If you mean higher than docked in docked, then no. If you mean higher than handheld in handheld, then probably it's possible (maybe even 720p because of handheld lower quality settings and no AA).
I'm working with Kirby567Fan on this patches and it's sharing similarities to some of my 60 FPS mods like Fire Emblem Three Houses, so I think my answers are correct.