Smoothing out damaged internal concrete floor

(sorry for cross-post but this might be more relevant here)

The concrete floor in our living room has been subject to a bit of damage over the past few months since the carpets were taken up and some plumbing work was carried out:

1) A 10cm wide by 10m long cavity was dug along the centre of the room to allow for new piping and concrete was laid down on top of this. As the concrete dried, the centre dipped a little lower than the edges (approx 3-5mm) so now there is a noticeable channel which will be visible when the carpet is rolled back.

2) Carpet grippers were ripped up, taking some concrete floor with it, so there are several small indentations.

My question is related to how I can "smooth out" these imperfections and fill in the concrete holes before the carpet is laid back.

Do I need to get some screed/leveller product for this? Is this what I need?

How long does it take to dry?

Thanks!