How to balance project tasks with finishing old work and how many publications should one have as an early career PostDoc?
I am a researcher in a related field.

Some general answers to your questions, which was advised to me when I was in a very similar situation.


To maintain a balance, it depends if there are 'cross overs' in your prior and current research. If there is very little or none, then you could do what I do, I set some time every alternate weekend and a couple of evenings every so often - depending on what is needed for the research.
One way to tell how many papers would be considered 'normal' - or rather, a representative amount of papers, would be to do a search on Google Scholar or similar - of particular authors in your field, in specific years.