I had this same situation when building my shed. It is 10x14. I excavated the dirt, poured a footer, and layed 6" concrete block. 4 blocks high got me above grade on the deepest side.
1. There can be debris in the valve causing the diaphragm not to operate properly.
2. There can be trash in the lines somewhere.
3. There is a large leak somewhere. Run the zone until you see water, it might take a while.
I have run Scag and JD zero turn mowers. The Scags are a much better mower, even the lower ends ones. I have currently mow about 6K sqft with a JD 7h19 54" walk behind. It is overkill for my little yard, but like you I was tired of using a 21" walk behind. I have better things to do than mow...
I do this a work frequently. Very easy to do. Remove the ballast and wire directly to socket. It does not matter what wire goes where. Satco makes quality bulbs, that is what I use. There are many options. You may notice the lumens will be less with the LEDs but they look much brighter when...
Those joists are rough sawn. You need brackets for rough sawn lumber not regular dimensional. I have notched timbers to accept standard brackets before. rough sawn brackets are hard to find. Only need to remove about an 1/8" to make them fit.
You don't need to precut before install. Start in one corner and work your way around. 90 ft is not that long. Use cove base adhesive with the wide tip. It sticks fairly well right away.
The builder did not install vented soffits? If not you can install the vents. In the attic you need to install the plastic or foam chutes on the roof sheathing so the insulation does not block the air flow from the soffit. Put them in every other or so space. No need for furring strips and foam...