Interesting questions. I can only speculate what kind of effect the delegations you are talking about would have on the votes of anyone who received them, but I think paying it forward a noble intent.
The question that I think is important to ask is how you would hope for them to use the SP? You mention their voting or posting behavior but don't give any real idea of what you are looking for there. Do you want them to be a beneficial angel, voting only to help others? To help themselves? A blend of the two? Only vote for people below rank 70/60/50 etc? As to posting behavior, are you talking quality/frequency/topic/resteemers?
If you can find people whose actions are likely to coincide with your hopes / respect your wishes, I think that would help decide how many recipients get how much. Only help others? Higher delegation, fewer people (hard to find I guess). Help themselves? Lower delegation, more people (easy to find). Somewhere in the middle? Looking at it this way reduces the emphasis on the time factor I think.
As to the criteria for the recipients, we all have our own personal values. What are yours? I think recipients should align with your primary core values and narratives you support.
If I were you, I might just do the madness of announcing a competition along the lines of "Win X amount of SP delegation. Write 250 words about what you would do with it and why." Does make for a lot of reading though I assume.
It would be helpful to know, for example, what 1000 SP does to the strength of votes. I am hammering out .03 votes now at ca 250 SP for example, and have no idea what 1000 would do, increase my voting to .15? I think its great you are looking to how you can contribute more.
That old Spidey quote comes to mind, "With great power comes great responsibility".
Cheers!
Great suggestions, thanks for adding to the post.
I really like your idea of "Win X amount of SP delegation. Write 250 words about what you would do with it and why." I think that will probably be happening lol.
I work out 1000SP as 2.5% of my current SP about, which is about a $0.115 upvotes at 100% on 1000SP.