In theory, "reserve" means it's a higher quality wine. This may be the best grapes were processed separately, or the winery may grade their barrels and segregate the best ones.
Cynically speaking, other wineries may make other choices. I've had "reserve" wines that were fantastic, and some that were pathetic.
If I was operating a winery? I'd make a "reserve" version of my best grapes, white and red, segregating on grape quality and individual barrel quality -- working with what I have. Aging timeframe would vary by wine -- like most things in winemaking, the wine decides, not me.
Number of bottles? As many as I can! Keep in mind that real quality is limited so I'll never get as many as I'd like!
Price? I'm too honest to price well. It's probably best to price just high enough that the average person will stretch to buy a bottle, looking to make sales in the long haul. A reserve wine supply needs to last long enough for the next vintage to be available. "Reserve" works when there is supply.
This is good marketing, which is a critical part of business.