Q1: Is the MEI Initial (oral) going to be a long one?
Q2: Is the MEI Initial exam going to be tested by DPE or FAA Inspector?
Q3. Does the student require to perform instrument approach in MEI (Initial) flight exam?
Q1; It could very well be. It is the " regular" CFI oral plus ME subject matter.
You can order a CFI/MEI PTS (practical test standards) online from ASA.
It spells out exactly what an Examiner (DPE or otherwise) needs to cover.
Q2: Either one, depends on the FSDO. If they are not busy they'll do it themselves, if they have nobody to do the test in a reasonable amount of time they'll authorize a DPE.
Q3: No.