Yes - I took the vent plugs out of the cartridge before putting them in. I didn't get any any ink in the vent plugs.
I've done at least six or seven cleanings. Interestingly, the first two or three showed some nozzle action - but after the seventh cleaning, I'm getting what's in the photos, above.
I'm not quite sure I understand your question about the cartridge model and where the filter screen is. I bought the cartridge from Inkjet Mall for the R2880. Can you elaborate?