I find this thread interesting because I've been in the same spot as these coms many times. Only SkySports ever provided me any background info on players, so other than that it was up to me. My strategy was first to check their records on AZ for how they did in tournaments during the current year. I would also look for any major victories. Then I would spend maybe five minutes with each player prior to the match chatting about their most important wins, their prior record against their opponent, sponsors, cues, etc. Age and hometown is a given. Any other background I could glean in a short time was also helpful. Many players I knew pretty well already, but there were always new guys coming up.
I liked to see how they view their opponent and what strategy it might take to win. Then I would stand back and watch how they interact before the match began. I liked to see that dynamic because it told me a lot about how they felt about each other and the importance of the match. Sometimes I would see them discussing "deals" (believe me I could tell) and I knew that would have a bearing on how they played. Some guys have a well cultivated rivalry (Dennis and Shane for instance) and others may even travel together.
One other thing that I think is very important and is often left out of the commentary by some of these guys is what's at stake in this match! Is it winners or losers side? How much money is on the line? Who will the winner (and loser) play next and when? Everything that makes this match important (Mosconi Cup rankings could be very important this week!) is worth sharing with your audience imo.
I like the new resource that Fargo provides with previous match records and I would advise the current crop of coms to take advantage of it.