"Will it be politically acceptable to arm UAVs?"
Already been done with Predator.
"A ground based controller will never have the same level of situational awareness as a pilot."
The ground based controller might have better SA because he may have more info feeds. If a pilot cannot see the enemy, then he has to rely on sensors in the same way as a ground based controller.
"Another thread on PPRUNE talks about "friendly fire". These incidently would inevitably be much more common with UAVs."
I disagree what do you base this supposed inevitability on?
"(particularly in the offensive role or with long range missiles) will not be entrusted to autonomous systems so a human bloke on the ground will have to OK weapon release."
Yes, but how do long range cruise missiles cope. Target ID does not need to have an operator with eyes on the target passing the "arm" code. It will be dependant on ROE.
"Then there is the issue of infrastructure."
More required for manned ac - longer runway, more fuel, more defence, more personnel etc. etc. UAVs have the potential to travel much further than manned ac, hence can be based in much safer locations.
"Basically, allowing software to control things without having a human ON THE SPOT to make sure things are OK is just asking for trouble."
Basically allowing a human to interfere will cause many accidents and has in the past. You quote various software caused crashes, however the Pilot didn't save the YF22 so how does having a human operator make it safer. The Mull of Kintyre accident has never conclusively been solved - many have their pet theories. There is no conclusive proof of what caused the accident - it COULD have been human error or it COULD have been computer error - to name just a couple of possible reasons.