Sure, man. The next iteration is planned to run concurrently with the 2020 PSL. This is basically to give the people interested in the real-life version of that Pakistani league something similar to join and have fun with. It's going to be similar to that, but not entirely identical. So, You can expect this to begin from mid-February.
Anyone that wants to participate, can participate in this. If existing managers retain their teams and there are no teams vacant that you can manage, you can ask to be the co-manager for existing managers.
Generally there is a certain number of retentions in place, after that, there is a draft where whoever picks the player they want first, gets them. There are no restrictions on that apart from the general foreign-player limit.
I hope this answers all your questions.