I'd like to install a lake pump to supply a) sprinklers, hoses
initially, and eventually b) a sprinkler ( timed ) system.

The lift is approx 21' from lake surface to use-height.

1. What's best: a) jet pump? b) submersible?
3 If I want to pump to automatically start when a tap is opened, how is
that done? Via use of a pump relay switch ? If so . . .where
should that relay switch be located -close to the pump?
4. I assume you stock/sell all of the above?