Medical Support Officers are as we're said the Commissioned medical support to the DMS, the are a combination of specialist Medical trades, ie Physio, lab tech, EH, Radiographers etc which used to be Med Tech Officers and more generalists and I have DE MSO's who have no medical background as well as people who have come from the ranks and were Air Traffic.
As to Cranwell SERE is usually for professionally qualified trades so, Dr's, nurse, lawyer, padre, and as MSO is not a profession then the majority do the full IOT, not 100% sure about physio as it is quite new but would assume that it is SERE. As to those coming from the ranks which course is done is handled on a case by case basis but I do not know one non-medical MSO who has done SERE so if you are not medical then prepare for full IOT.
Whether medical or non medical you are in the same postings and promotion slots so especially at Sqn Ldr and above then it is one big pot. True, OIC of an XRay dept is likely to be a MSO with a radiography qualification, but in Bastion recently the 2 ic of the Field Hospital was a tankie but had come over as an MSO ( this was army though).
As to pension I Commissioned after 15 years and kept all my Service time. In nursing your graduating rank was dependent on how long you had been qualified as a nurse and was nothing to do with previous rank or time served, not sure how it works for others.
If you have any questions let me know.
