No, the MEP is not the same as the SEP.
You can only renew it with a Class Rating Examiner (CRE).
Similarly the IR, you can only renew/revalidate it with an Instrument Rating Examiner (IRE).
An IRE is also likely to be a CRE (although this is not true the other way around).
If you are doing the IR in an aircraft, not an FNPT2, yes, the test is a combined MEP and IRR test. If you are doing the IRR in an FNPT2, you also have to do a separate MEP renewal test in the aircraft.
If you did the IR last year in an aircraft and you revalidate the IR before its expiry date you can do it in an FNPT2.
If you are not planning to fly an MEP aircraft, I would not bother with the MEP renewal test - the airlines are not interested in whether it is current or not.
Linda Mollison