Does anybody have tips for managing large projects with Studio?

Hello SDL community, 

I am about to do my first very large project in SDL Trados. I have received 30+ folders with 1000+ JSON files of varying sizes.

I have previously mostly worked on small and medium-sized projects in Trados, and I would like to hear if more experienced users have Trados-specific workflow tips for large projects. I am looking for general tips for how I can manage the project and stay as organized as possible.

Some more specific questions:

1) I was planning on opening several files for translation together since many files contain only a few words or sentences. If I select several files and open them for translation, will they then be merged or does the original format of them stay intact?

2) Something that, in my mind, would be incredibly helpful is to add comments on a file level. Sometimes, in Trados, I open a file only to decide to come back to it later. At this point, I would like to have the possibility to add a comment to that file (visible from the files view) that tells me that I should come back to it later, or why I decided to wait with it. Otherwise, I keep opening the same file over and over. Is this possible?

I appreciate any tips that could be helpful to manage this project in the best way possible. Thank you kindly.

(I use Trados Studio 2021)