What's the benefit of watching 30 & 90 day metrics?
There are a lot of benefits, actually. Arbitrage is sorta volatile, which creates the price gaps you can take advantage of. A downside to that is if the product dips too low in price or slows down too much in velocity, you're stuck with something that loses you money. Verifying the product history is well worth your while, and Leadgeek makes it easy to check out.
Will I get the buy box?
Quite likely, yes! That's why the current competition is included. For example: if the buy box is controlled by a merchant fulfilled seller, swoop in and grab those sales out from under them. Does an FBA seller have the buy box? Match and share, there's plenty to go around.
How are these values tracked?
With a really cool tool called Keepa. Keepa tracks the history of a product for days, weeks, months, or even years. The buy box competition is determined a few minutes before the lead is posted.