a) See staff reply on possible premium themes:
b) Randomly? No. The main posts page of a blog displays your latest posts in reverse chronological order. In the conventional blog layout that's from top to bottom. In Imbalance it's left to right and top to bottom, and the complication is its "masonry" layout: if a-b-c-d is the first row of posts, and c is shorter than the other three, then post e will show up below c, posts f-g below a-b etc.
c) In another thread you've said you want one column with content that doesn't change, plus two columns of posts. So I don't really see why you have selected Imbalance. You'd better try a theme that has a sidebar and two post columns: Inuit Types, Chateau or Under the Influence. Or maybe Suburbia: sidebar plus posts in rows of four, or a row of two for stickies (double width).
d) An alternative that would allow you to highlight selected posts (but above, not next to regular ones) would be one of the themes that can display sticky posts in a slider: Forever, Fresh & Clean, iTheme2, Nuntius, Selecta, Splendio, Twenty Eleven.
e) Yet another alternative, if you are prepared to update things manually, would be a theme that has two sidebars and one post column.