Hi @mariusfebruary,
I am a small fish here in the Steemit world. I did not invest so far, but I do want to put in some money in the ecosystem once the prices will go down a bit after the recent increase :) I am here for about 6 months. Sometimes more active sometimes not. I see your point with quality posts and I had the same issue in the beginning. I came across @pifc where other steemians look for small accounts creating good content and support those who just started. The main problem here is that some people think growing is easy and fast but you have to put a lot of effort into it to grow steady.
To your questions:
Should I base my upvotes solely on the quality of the posts and thereby support people who already know how to produce?
I think you should consider autovotes on profiles you like because after 15 minutes the curation is the highest. When you set it up you do not have to worry about that you might miss some upvotes and therefore a curation. With @crypto.piotr mentioning it in one of his posts I learned that I can earn some extra by just doing that with the accounts I like :)
Should I assign some of the upvotes to people to encourage them to become great authors?
I might do not speak for everyone, but I consider this as a dream. In my case it is sometimes really frustrating when you do some research and want to produce an interesting post and have a payout of only 0.05$. I think with upvotes you can definatly encourage people to get better and to work hard so that you also have the pleasure to read interesting articles :)
How much should I direct towards diversification? For example, to make the place more interesting by upvoting authors from many countries (that may follow ethical rules that would be called unethical elsewhere)?
This is a more difficult one, but I would say that you can choose your beneficiaries based on your own opinion. If you like the content someone produces it does not really matter where he or she is coming from :) There are hidden gems from every country.
Note:
I totally see your point, that this project is also monetary driven. I mean what is wrong with it :P And as a normal business man, I can totally see that you are driven on ROI.
With the points I made in the beginning, I think you are good to go :)
I might have not the best Steemit expertise, but it is an ongoing process and I learn every day.
Have a good start into the week,
Max