Thunderroad

In threads about Priceline, I've seen posts explaining that Priceline tix don't accrue UA miles. The Priceline site claims that if you select the "Choose Your Flights and Times" option (as opposed to the "Name Your Price" option) "most flights eligible for frequent flier miles." Is this a runaround from Priceline, or is the site correct? FWIW, I'm looking at flying international business class on UA for at least part of the trip.

Also, anything else I should be aware of/beware of in dealing with Priceline? I assume that if I purchase a business class ticket from them, I can go ahead and call UA or whatever airline to then get a specific seat assignment. Is that correct?

Finally, I recall one post claiming that upgrades are possible on UA flights bought through Priceline. Anyone have any experience with this?

Thanks for any advice.