Sorry, there really is no answers to your questions.
The truth is, the developers don't know. The witnesses don't know. Nobody knows.

HF-20 wasn't thought through.
It was not implemented properly.
In order to fix what they broke, the developers manually tweaked things, and this will have serious effects in the future.

1. A hard fork changes how the block chain operates. Everything works different now then it did a few weeks ago. For most people, there isn't much change at all. HF-20 added the mana system, so they could control resource allocation more finely.

2. There is no policy for handling this judiciously. If it was me doing it, it would have been done in two steps. Step 1, add mana accounting. Step 2 (after mana calculation has been shown to work) switch to the resource allocation system. But, really it was just a group of developers saying this is our best guess, push it on the public.

3. We don't know. There is a very real possibility that minnows can find themselves out of resources. If a lot of new people come on board all at once, and STEEM price changes drastically, minnows could be found to be without the resources to vote rather quickly.

4. My guess is about a year. This HF-20 has changed the underlying behaviour of many things. And its ramifications are still unknown. We will not see the end of this for a long time. I am still waiting for a witness to have to reboot their system and replay the chain. And since it took some manual tweaking to get to our current mana position... after the reboot the tweaking will not be there, and we may have servers with different numbers running.

Oh yes, they changed curation rewards. It used to be a 0 minutes, all the curation went to the author and linearly changed to all the curation going to the voter at 39 minutes.

Now it is at 0-14.99 minutes all the curation goes to the rewards pool, and at exactly 15 minutes all the curation goes to the voter.