I want to bend a couple of shart rdius turns and forge an eye ( m5 hole) in each end of some 8 or 10mm aluminium rod.
Looking for advice on whether it should be done hot or cold and if hot should it be quenched or left to cool naturally.

Hmm depends on the ally grade.... If its bog standard alloy bar from the likes of metal supermarket I would go with heating to anneal (spread soap on it and heat until it blackens), bend / forge then re-anneal. I've squashed the ends of alloy rod in a big FO vice, prior to drilling them for M5 bolts. You can do it with an engineers hammer if you are careful but its less precise. Remember to file a slight curve on the end of the flattened bit.

If you only bend it once and can make the full bend in a single movement then it should go cold - as Phil says, heat wouldn't hurt but you might ultimately do more harm than good.

You probably have no need to flatten the ends. if it needs to sit flat against something then just flatten that side(s) with a file and pop your hole in.