First, congrats to Carmoisine for (a) getting is so right, and (b) taking the trouble to spell out to those who will not listen what they should take very seriously. Those seem to include JW411 who knows "a lad (from the local flying club) who is earning €75,000 a year gross as a Ryanair F/O". Great news for the lad from the local flying club, but not a good guide to life in Ryanair.
While it could well be true JW411 it does not mean that the latest basic for a Ryanair captain is not €58,600 (the correct figure according to REPA which talks of referring actual documents). Of course that is the "basic" - but the year one figure is 90% of that - yes it is even less! Maybe that answers your question "Where on earth does this figure of €56,000 for a Ryanair captain come from?".
As for "On a previous Ryanair forum, a TRE admitted to earning €160,000 (£108,000)" ... well even if true it is so far from the reality for most FR pilots that it serves its purpose to have it quoted here from time to time. You seem willing to believe it it is real reflection of life in Ryanair, so it served its purpose for you!
The problem JW411 is that there are so many contracts, so many fudges and angles and pilots willing to do different deals that you never know anything in Ryanair with certainty. Well, apart from one thing, that is: each year the average pilot pay goes down. The rate of decline is determined by the number of pilots willing to allow themselves to be entrapped in circumstances in which they feel they have to say yes.
But, increasingly, people have little sympathy for the lot of them as they create their own mess. It is the spread of the disease to other other airlines that is the real problem.