I follow almost 1300 people. I don't even know how it got to that. Probably 2% of those tweet regularly, about 0.1% tweet anything valuable or interesting. It's just too large to go through and curate now.
I don't know who sees my tweets. There's no "viewed" count or "who viewed" your tweet. I would think, if it flows past someone's eyes, it would be nice to know that it did, and how many times.
Promoted tweets should have a bold background color. I never notice when one is promoted other than it feels like it might be.
And something that really can't be fixed IMO is to have Twitter only show things I will be interested in. I would like it to be able to read my mind. Is that really too much to ask?