[Trainer-Talk] Move from iPhone to Android - Help?

[New Vision Tech Center]

Hey All,
I'm thinking its time to move over to Android and get familar with the
AT software on that side. I've been using iPhone since the 3Gs with
VoiceOver and Zoom. I'm an AT trainer but also a low-vision user. I'm
thinking of getting a Nexus 5x, since its a vanilla Google experience;
an I'm thinking I'm less likely to deal with inaccessible cruft from a
manufacturer or carrier.

Three Questions:
1. Since there's no hardware Home button, I'm wondering with Google Now
Voice Assistant, is there a way to program a gesture to invoke it? Like
one of the right-angle gestures or something? I'm use to Siri with the
Home button.

2. Is there a quick way to invoke the dictation function when in a edit
field. I know a down-and-left gesture, which serves as a back button,
will stop it but is there an equilvent to a two finger double-tap to
start it? Any hack you know of or alternate keyboard that might solve this?

3. Google, lists the Color Inversion as an experimental feature? Have
any of you experienced any problems with it? does it flip all colors
around? or is it like Windows phone which leaves JPEG pictures the right
color?

Any other additional insights are welcome. Thanks.
-David

PS- I've still got my iPad Pro, so I can keep in touch with what's
happening on iOS.