I'm not with FR, but I can tell you something about german taxation laws.
There are five kinds of taxes in Germany. Three of these are social and two salary.
Salary:
Einkommensteuer: Salary tax, which goes linearly from 24-38% - and now come the complicated part - continues to go up to 42% however only on the ammount above 55.000euros. You will have an ammount of 8400€ that is free every year and is not counted into the total amount.
Solidaritätszuschlag: 5,5% of your annual paid taxes. So let's say you are paying 20.000€ in annual taxes. Hence you would pay 1.100€ in "Soli". It's a tax that was invented after 1989 to help rebuild east-Germany. Nobody really knows why it's still around. Ask Merkel.
Now to the Social taxes:
Krankenkasse: Health insurance. In Germany you will have to pay 50% of this if you are employed and 100% if you are self employed. There are a thousand different companies to choose from. Private and "Allgemeine" basically public ones. One sounds fancier than the other, but in the end you can get the same coverage from both, hence one (allgemeine) is a lot cheaper.
Rente: Pension. This is split up 50/50 between you and your employer (Ryanair) or yourself if you have your own company. So 9,35% if you're employed or 18,7% if self employed.
Arbeitslosenversicherung: Unemployment tax. 3% if you are employed and 0% or voluntary 3% if you are self employed.
In the end, the McGinley contracts will in Germany count as self employment.
On top of all these taxes, the german fiscal authorities are usually quite keen on costs that you produce for work. E.g. you'll never have an issue getting tax exemptions for basically anything you'll need for work (of course you'll need two new macbooks each year, an iphone, a xerox printing machine etc). You are even able to declare a room of your appartment as working space and claim an exemption for it rent/m². I would suggest you to get a GERMAN tax advisor and not some shady company that is connected to FR.
Hope this shed some light into the dark.