1) No.
Advisable, of course, but then knowing what
all the knobs in your plane do is very advisable
And you need to have a much deeper knowledge of "knobs" to fly GPS/LPV than to fly an ILS for example.
Most pilots who fly behind an IFR GPS don't understand how to drive it to the full. That is fair enough if you are not using the extra modes. For example I never bothered to learn the full GPS RNAV approach + missed approach waypoint sequencing (or not sequencing) peccadiloes of mine until recently. For LPV ops you do need to read the manual and learn it.
2) No idea what that means. All LPV approaches do need EGNOS (WAAS in the USA).
There is a level below "full LPV" whereby the GPS shows a "glideslope" which is not the actual ILS-like LPV glideslope but is in fact the continuous descent profile depicted on the approach plate. And with suitable avionics this too can be flown using an autopilot, like an ILS. The minima are the nonprecision published minima. The benefit of this is that you get continuous vertical guidance. You need EGNOS for this too.
I don't follow the details of this stuff because my GPS is RNAV approaches only, and it would cost me about £20k-40k to get LPV (or PRNAV for that matter).