Point one. For Ryanair you need the right to live in the EU and believe it or not the UK is part of that
So only if you are in the EU and thus no visa is needed.
The second thing is that they have enough low houred guys for the moment but are always interested in high houred guys.
Salaries vary per station in Euros or Pounds. The Pounds thing is probably to keep some healthy competition with Easyjet to keep the salary high
Loftie your point is?