to answer your questions:
1. the design of the bowl and optics of the A3 is like the design of good performing OEM projectors like the FXR and TL kaya the performance is comparable. I still have those oem projectors in my line up by the way. yes pwede mag-revert back to stock halogen and you will only do this if you want to transfer it to another vehicle. I will guarantee that you will not revert back to stock halogen dahil meron problema yung hid syst that I installed.

2. That is correct. When you do a retrofit, the halogen reflector bowl just holds the projector and wala nang ibang other function yun pag dating sa lighting output so walang glare. The projection nung light will be handled by the projector bowl and the glass optics. Meron some hl na will produce a little glare from the bezel pero mahina lang and depends on the HL, I will suggest to smoke it. Yung City sa taas is a good example of that. We smoked the bezel kasi mahaba yung part sa baba na pwede tamaan ng ilaw at pasok ng konti yung projector. Iba yung design nung reflector bowl nung hid headlamps like the Civic 2.0 and the Forester. If you will examine the hid bulb vis-a-vis a halogen bulb, first thing you will notice the electrode is 90deg off and orientation. Iba ang bato nang ilaw so iba ang design nung reflector bowl na nag-re-reflect nung ilaw.