1) Yes. I've been constantly generating since around January.

2) Yes.

4) Yes. Many.

5) Generating is still profitable, even on my ancient computers. Bitcoin uses $0.25 per day in electricity, but I will make on average $0.60 in Bitcoins per day (and I actually value Bitcoins more than the market price). Even if it wasn't profitable, I need a running bitcoind, and I might as well have it helping the network.