Despite Ryanair prices constantly increasing you now have to self check in at Stansted - that’s if you have prepaid for baggage. Otherwise you have to lug it around the airport for 2 hours and then onto the plane. So it makes sense to buy priority- the queue to board is also slightly shorter.
At Lisbon Ryanair is based right out at Terminal 2. It’s a long coach ride ( Very few seats) to baggage reclaim in T1. Be warned that on return trip the facilities in T2 are appalling. If you want to eat do so in T1 before catching the bus to T2. The food is better once you have gone through security. You can also expect a long queue at passport control.