Deb,
Impossible to give you a definitive answer.They have four or five airbridges at Faro but seem reluctant to use them for some reason.The last three times we've landed there(all recently),we've disembarked via steps when all airbridges were unused.
I think you'd be safest to assume that disembarkation will be via steps and request a wheelchair lift.

I used to travel with my mum who had the same problems as yours and found that if we let the airline know in the UK that assistance was needed in Faro, it was always available for us.
Recently, in Faro airport, I saw a lady in a wheelchair being lifted by a sort of elevator type crane ( No comments, Sagres!!!!) straight into the airplane as she couldn't use the stairs. So I think this is likely to happen for you if you ask in advance and also remind the cabin crew just before you land.
Hope this helps.
Pat

It seems that unless you're travelling with TAP, who seem to have priority at the Jetways, you're always bussed.