Unlikely that he's still alive, but the evidence of a controlled landing makes the whole thing more puzzling from a psychological perspective. Why slowly and consciously drag it out until the very bitter end when you've already completed your suicide mission?

While not impossible, it's unlikely - he'd have to survive the crash first (and given it's likely the plane ran out of fuel and power it would be more difficult), and even then, given he went all the way out to the middle of nowhere, it would not have been his intent. Even if he did survive the crash and get out before the plane sunk and got on a life raft with a planeload of supplies like food and water, he'd still have a very low chance of being found or washing up somewhere. And it took a while before they even started to look in the general direction of where the plane would have crashed, so it's not likely he'd be found that way either. It took nearly a year for debris to start washing ashore in Africa.

In the middle of the Indian ocean, thousands of miles from land. It's unlikely.

Maybe a rendezvous with a recovery vessel ? Any evidence that he had access to piles of cash ?

This is not true.