1a. Subtract is a good option, it will set the flags in the status register. Z being set means the values are equal, the C flag tells you which one is bigger. From that you can deduce if it isn't bigger or the same, the value must be smaller.
1b. If by ATE you mean Automatic Test Equipment, yes some testers use stored test patterns (aka test vectors) but what has that go to do with PIC16F1783 ? By the way, I am qualified by HP, Genrad and Teradyne in digital device modelling and test systems programming.
Brian.