4 in. x 10 ft. 2 Hole Triplewall Pipe

Yes. The best way to lay this in a trench is to (a) first line the trench with enough fabric to cover the walls and fold over the top (b) lay the perforated pipe in the trench, glue or screw the joints together (this is required if you live where the ground heaves from frost) (c) cover the pipe and fill the trench with gravel, (d) wrap the fabric over the top of the gravel, holding in place with yard, staples (d) you can cover with sod or stone (dry bed) as desired. A 2% (1/4" over 10' length) fall is preferred. Less fall can be managed if the drain pipe is daylighted. It's important to have the GRAVEL AND PIPE isolated from the dirt (bottom, sides, top) This will serve to block any soils and fines from entering the pipe, and will last for years. You may want to have a cleanout tee every 30-40 feet if you are draining roof gutters into this pipe and ou live in an area where your gutters may collect leaves Otherwise, the clean-outs generally are not necessary.

A two hole pipe, with holes facing downward at the 5 and 7 o'clock position will allow liquid (water or effluent, etc.) to be carried along the length of the pipe so as the liquid rises (in the pipe) it is distributed more or less equally from the holes along the soaking or distribution bed. For this to be effective the pipe slope must be minimal and fairly close to level: about 1/4 or so per 10 feet. Any steeper slope and the liquid will rush down the slope and collect at the end. I've never had a need for three hole pipe so I am not sure of how it would be used.

Yes is stronger than the corrugated pipe but still can only be buried up to approximately 3 foot deep after that you made me stronger pipe

Yes, the drain pipe can be cut to length with a sawzall, or if you don't have one, a hack saw will also work.

The first part of the answer is - it depends on how deep and wide of a trench you are making. If you dig a trench that is 12" deep and 6" wide, and plan to lay 1" of gravel in the bottom, followed by the drain pipe, then covering the pipe on both sides and the top with 1" of gravel (filling half the trench with gravel (6"x6") - then covering it over with 6" of dirt), it will take approximately 12 cu. ft. of gravel for 60 ft. in length. If your trench is wider or deeper, then for each square inch when increasing in both dimensions, you will need an additional 0.4 cu. ft. of gravel. So, filling a 7"x7" trench with the pipe requires approx. 12.4 cu. ft., filling a 8"x8" trench requires approx. 12.8 cu. ft., and so on. It also depends on how thick you want to make the gravel around the pipe - these estimates are all based on appros. 1" of gravel surrounding the pipe on the bottom, sides, and top where there are flat surfaces; the four "corners" of the trench will have more than 1" because of the curve of the pipe.

NO !!

It depends on how deep you are building the retaining wall if it is over 3 ft high then you need a stronger pipe

S&d fittings

A leach line needs gravel hence the word leach line it needs gravel so that it can Leach out of the pipe fabric is only there to prevent debris from getting into the holes

the pipe is very soft. Do not place close to the surface where transport can pass or the driver mows the grass.