Confused about Workflow with Davinci Resolve 15

Hello all!

I am the most happy guy on earth with my two Blackmagic Ursa Mini 4.6 K. Thank you Blackmagic for turning so much possible and accessible to so many people.

But I am the most confused too. I search all over the internet but couldnt so far find a SIMPLE question to this.

My production workflow is explained in the imagem attached to this post (and yes, I know there is Fusion inside DV 15).

I shoot using Blackmagic CinemaDNG raw format on my Ursa Mini Pro 4.6K.

In order TO PRESERVE THE INITIAL QUALITY, I have three questions:

A - What is the file format I should use to export from DaVinci 15 to Adobe After Effects (10 bit the minimum)?

B - After I made my VFX compositing, what file format should I use to export back FROM After Effects to DaVinci Resolve 15? (and I dont want to introduce Adobe Premiere Pro on my workflow).

C - Finally, after grading in Resolve, what should the export file format should be in order to preserve the BEST delivery quality, no matter the publish platform will be used in the future?

Can please somebody help me on this questions?

Thanks to you all, and for your time.
Rui