To add the MEP to the IR reval flight, you need to add (all as visual manouevres) stalls, steep turns, flapless and normal landings, rejected take-off and emergencies; as 1/60 says it usually adds around 15-20 mins to the flight assuming all goes well.
Renewal (after expiry) of the IR is the same test as an IR reval (ie no extra items) but must be done in the a/c - you can't renew in a simulator. If you go over 5 years then it has to be done with a CAA staff examiner.
You can't renew or revalidate a ME IR in a single engine a/c - if you did the test in a SE then you would get an IR restricted to SE only and would have to take a further test (in an ME) to reval/renew the ME IR.
Hope this clarifies things.