Well, a restore from backup made things a LITTLE better.. really not sure why this beta would produce noticeable (and for the odd doubters out there it is noticeable) lag and UI glithiness.
Also, I have the stocks app on the mail screen, it should be displaying a single stock and current price (from the stocks app on the phone of course) and it won't display anything since the new 3.2b1 update. Odd.
Re your first point: because it's a beta. Not trying to be snarky, but they don't necessarily make these so they pick up where the last release version left off. There may be code they're testing that they know impacts UI, but they still need to see how it works in the wild.
Regarding your second point: I am not on the beta but ever since upgrading to 3.1.3 last week, all I get is the little crooked arrow thing rather than a stock price. So, I don't think it's unique to 3.2b1.