Everyone is entitled to legal representation; if you can't afford one, one will be provided by the state, however, that is not your question.
Clearly lawyers in Europe are massively underpaid if the best of them can only charge 200 Euros per hour; a middle of the road barrister in Sydney will set you back about $800.
How is that kind of defense funded?
The dependent may be wealthy, or have a wealthy family, or friends, or have the defence funded by a benefactor, or have the lawyer work for free or at a discount, or ...
Does the lawyer take it on for cheap for the thrill, or do lawyers always work for regular pay?
Like anyone else in business, the lawyer sets his own rate which may be zero if he wants. It's unlikely that it is for "the thrill" but it could be for exposure, or because he is a friend of the family, or for the challenge (it will be a difficult case to win), or because he believes in everyone's right to a fair trial, or ...
If so, does money just arrive transparently/opaquely in a fund from donations from conservatives similar to the defendant and by jihadi benefactors?
Possibly. Unless there is reason to believe that the funding is sourced from criminal activity how anyone spends their money is up to them.
Are they tracked?
Why would they be?
Can they be anonymous?
Can donations for a defense be sourced internationally?
To be clear. If this man has done what he is alleged to have done then he should get the fullest punishment that the law provides. However, until the allegation is proven, the man is entitled to be treated as innocent and is entitled to defend himself in court to the best of his and his lawyer's ability.