Most bricklayer will not use 1: 3 half brick thick. That means bed joints of 30mm thick. I doubt you can point it properly. The work may not look nice and may crack because there is no flexibility in the mortar.

Depends on how good you are at using a trowel, what kind of wall you are building, what footings you’ve got and how you plan on pointing it.

Normally a ton bag / bulk bag of sand and 6 bags of cement will lay 1000 bricks (that’s what I go off). Hope it helps.

Only when I work out how much sand and cement for a small job I work on the basis of 25 kg bag of sand lays 22 bricks 1 bag of cement has four shovels of cement so one bag of cement does four bags of sand .
1 bulk bag has 40 25 kg bags which a 1 ton bag will lay 1000 bricks