Everything you buy is predicated on the height to which the water must be pumped. (Or the maximum height to which you'd
ever need to pump on the lot—say, in the case of a well failure.) My location isn't Winnipesaukee-extreme at 25'-height, and we get by fine with a 1" diameter intake pipe and ¾-HP pump.
If we're talkin' less than six feet, you could get many seasons of irrigation with spending less than $100—for everything!
Otherwise, I'd double-up on the hose clamps at every fitting, run the pipe as deep into the lake as possible to limit stoppages by algae, and would buy extra pipe connections and clamps while you're at the hardware store. ("T"s, "L"s, and straight connections).
Keep the foot valve at least a foot off the bottom—even if "disturbed" by an errant anchor. The orientation of the foot valve is not important. (Up, down, straight).
For ease of maintenance, you might consider special Marine hose clamps that eliminate the primary complaint—rusted screws. Test with a magnet: the best clamp screws, being minimally magnetic, resist being lifted by a magnet.
You'll need bricks to keep the intake pipe from floating to the surface, and cable ties to secure the bricks to the pipe.
More reading on the topic:
http://www.winnipesaukee.com/forums/...ghlight=bricks
http://www.winnipesaukee.com/forums/...ghlight=bricks
http://www.winnipesaukee.com/forums/...ighlight=valve
BTW: You'll
never finish this on just two trips to the hardware store.