There is an easy to fit oil tank drain valve from a company called Quick Valve, see page 3 of the Alternative Parts List on a sticky at the start of this forum threads. It makes it easier to drain the tank and then you just need to remove the "dry" sump plug to drain the final small amount of oil. Sump seal details are also on the list.
As for the AN type fittings for hoses, I have seen some done but it is a lot of trouble for not much return, there doesn't seem to be a problem with oil hoses coming off. As the oil hoses do chaff and have been known to wear through, replacing them with braided hoses is worthwhile IMHO. Merlin Motor Sport do some good quality hoses with a suitable temperature rate. I have details if you require them.
