I believe there were eight spare engines at the start of the project and they have used two. The latest incident would mean they are down to four. I suppose it all depends on what else they find when they remove the errant engines. Quite happy to be corrected if this isn't the case.
Yes, they started with eight zero timed engines of which four went into the airframe at the last major. Two have been replaced since 'first flight 07' as a precautionary measure at Rolls Royce request and there are still two zero timed engines available for use.
I've heard rumours that the two low timed ones that were previously removed may be allowed back into service, but as yet it's not (at least publicly) known whether that will happen.
It's a damn shame this has happened now though as they were very close to raising enough cash needed to get them into the display season. Still, nobody hurt, and the aircraft is in one piece so just awaiting more news and hoping for the best really.