Starting an area of yellow grove (I think...) and not sure how many divisions to plant?

I have a fairly unlimited (and free!) supply and a large-ish area that I want to cover... Is it just a matter of more is better? I keep reading about how quickly this stuff spreads - so will 3 good size divisions (5-12feet) give me a good start, or should I just keep on digging!?

Also, what is the easiest way to accurately identify the variety that i have?

Can a grove of bamboo be thinned out? I like this type of bamboo, but I'd prefer it not to be quite as 'untamed' as the grove that I'm digging from... Any thoughts appreciated.