For only a 1-1.5 acre lake, your CFM will be low enough that 5/8" or 3/4" lines will go many 100s of feet before pressure loss is an issue. Both are easy to find. Esshup mentioned larger tubing.. shouldn't need such for your application, but I did find a place that sold 1" x 500' for $110.
You want the pressure gage and pressure relief at the pump, that's your max pressure at discharge. The manifold wants to be at the pond where you're splitting your long-run line into two or more to go to separate diffusers.
May also want a moisture trap at the pump if it's downhill from the long run. Don't want water rolling back into your compressor.
