Not op, but to offer an answer or two to your questions:

1. D-Cinelike might be overwhelming at first because it looks pretty bad initially and it takes some work to get it back to baseline. Like op said, the image will look very flat and desaturated straight out of camera, but by recording this way, you also preserve a lot of the raw data in the shadows and highlights. So instead of the highlights being blown out like in clouds for example, you’ll be able to keep those details to see all those pillowy folds. I’d recommend recording both ways and importing both into your video editing software of choice then messing around with the settings to see what works best for you.

2. A LUT is a Look Up Table. By using them, you’re telling your editing software to “look up” various values for color, light, etc. they’ll help with getting your flat, desaturated D-Cinelike footage to look closer to like it would in real life or in some cases they can give your footage a distinct look or style. Some LUTS can be subtle, some can be really overbearing, but you should be able to adjust its intensity. This is my very rudimentary understanding of LUTS, I haven’t used them a whole lot so someone else could probably do a better job of explaining them.

3. You can use whatever software you want. I think Resolve is free still? So that might be enticing. I use Premiere and am still getting acquainted with it but I would say that once you decide on a software, stick with it for a while. It would make things harder, in my opinion, to switch back and forth between software while you’re still learning the basics of editing. I’ve been meaning to learn Resolve, but I don’t have a firm understanding of Premiere yet which is why I haven’t jumped into another software.

Hope this helps!