Since Garmin GNS 430/530 has the 8.33 capability, do you put Y into equipment when filing flightplan for usual VFR flight (below FL100)?
It does no harm.
Your other Q I don't have a proper answer for.
I always file SYRG/S.
There is no evidence that anybody in Europe cares what equipment you declare, except that Eurocontrol will reject a flight plan if
- you file above FL195 without a Y (8.33)
- you file above FL270 (?) without RVSM
- you file a FL which is above the ceiling for that type in their database
but I see no indication ATC uses, or even sees, the declared equipment.