The pattern was designed specifically for stripes, so it is a plain, garter stitch pattern with minimal stocking stitch detail on the raglan stripes. You can however knit it in one colour; there is after all no rules. If you do decide to change colour, and you want a clean stripe, make sure you change colour on a right-side facing row.
Colour changes are not specified in the pattern. Your canvas is blank; colour it any way you like.
As this is a Measure & Make pattern, I cannot predict your yarn requirements. The pattern will work for any yarn weight.