Checking Squadron's publication Part 1 on the Emil, I found no reference to the splitter plate located at the front of the oil intake. I don't think it was a particular characteristic to one frame, since the engines were the same when production switched over to the E-4. Only later was a more powerful engine introduced, noted as the 109 E-4/N, though most were produced with the earlier engine type as found in the E-3.
Modeling Madness reviewer Scott Van Aken has a build review of both the E-1 and E-3 and states that after engine maintenance, usually this piece was left out as it really served no purpose. So with that, if you don't have an actual photo reference, the rule of thumb is if the aircraft has been in service for quite some time, it's likely without that piece.
I've also noticed several reviews of Airfix's 109E-4 stating the splitter plate should be there because it was not provided in the kit.
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For the other detail, I think a photo might help shed more light on what you are inquiring about.
regards,
Jack