KL Flights between AMS and DUB are not operated by KLM but are codeshares with Aer Lingus.

This leads to certain oddities when booking and travelling. Maybe someone can help explain them to me.

It seems AMS<>DUB is not bookable on KLM at all. On klm.com that connection is not available as a direct flight but only via CDG on AirFrance/CityJet. Third party sited only have AMS<>DUB as an EI operated flight.
If you are booking XXX<>DUB however klm.com will happily offer you a connection via AMS with AMS inbound leg being KLM and the DUB inbound one being KL operated by EI.

My understanding is, that EI is basically a LCC and luggage as well as snacks/drinks have to be bought extra.
How is that in case one is flying on the KLM ticket?

KLM Manage My Booking is telling me that my luggage allowance should be two bags on the TXL-AMS-DUB part and one bag on the DUB-AMS-TXL part. Are the FB luggage allowances not granted on the return flight?

What about food? If one books a Air Europa flight with a KLM number there's a not that the flight only has limited on-board service. This is not the case when booking Aer Lingus. Any ideas?

What about Lounge access? The KLM website says there's access to the EI lounge in Dublin but posters here are reporting that benefit is not always granted...

Thanks.