PCX and Vario shares same engine. just design are different. or do you mean PCX hybrid?

i think you already had your answer in mind.
Go for it.
it is cheaper and look more eye catching.20km journey is ok.

ok. Best would be NVX due to ABS.

Looks Vario or NVX

Long distance comfort, PCX, NMax. since only 20km, still short journey. but if you consider long distance, PCX or NMax is better as riding position helps.

Spare Parts: Yamaha is easier to source compared Honda.

Wobble only if you hit a stone or pothole.
All bikes will wobble when lorry or trailer passby as the bike are lighter and only 2 wheel.
the lower the CoG, the more stable the bike. be it scooter or big bike

hhh. just avoid lorries/buses
either u ride faster than them or u let them overtake youmake sure at least 4 feet/1.2m distances

this is life of riding motor on daily basis. just be careful on the road.