It's hard to know without knowing your electricity rate. On top of that, we don't really know how quickly ASICs will come online. If I had to guess, though, I'd say mid-January.
Unless the exchange rate rises from here, block 209,999 is likely the last block that anyone mining with a GPU and paying normal rates for electricity (e.g., $0.15 per kWh) can mine profitably
It's hard to say. With the exchange at $12, electricity at .15, and reward at 25btc, I'm still showing a profit for most GPU setups at a difficulty of 5,000,000, and I haven't updated the GPU section of my spreadsheet in a year, so there might be better ones in terms of performance. In this case MH/J is the most important factor.
As an aside BFL FPGAs are just above 11 months ROI under that circumstance.
