Is there some sort of queue carried out within the Bitcoin node to retailer all of the incoming transactions earlier than including them to the mempool?

Merely the community buffers.

No less than within the present Bitcoin Core implementation, messages obtained from friends are processed one after the other by taking them from the community obtain buffers. If that message features a transaction, it is going to be processed (together with including to the mempool if relevant, and relaying to different events) earlier than persevering with to course of additional messages from the identical or different friends.

Clearly, that is an implementation element, and different Bitcoin software program could function in a different way.