Questions about BL stuff.

[BrianG]

Well, you pick a motor that will run at a maximum of ~35000rpm with the battery voltage you are using. For 16 cells, you need a motor with a kv of around 1800. The 9XL or equivalent is a good choice. You can always use a motor with a higher wind, like a 12XL, but then the top speed won't be as high. Sure, you can gear up, but you'll start stressing the ESC and batts.