Hoh boy Lotta questions.
Let's go in order:
Nature and ability are hereditary, I THINK. So get a parent with the nature, ability, or both that you want and breed them.
Machamps abilities are Guts, No Guard, or Hidden ability Steadfast. Depending on the kind of Machamp you want (attacker? Defender? Speedy?), you go with that.
IVs are RANDOM. So... Nothing you can do bout dat.
As for moves... Here is every single move Machamp can learn, on this link. Choose what you want and go for it.
Passing on moves: here's bulbapedias say in the matter.
EVs: babies start with 0 EVs. So... Again, nothing you can do.
And as for your last question, it doesn't matter if the parents are machokes or machamps, as long as they evolved from a machop or is a ditto, you will get a baby machop.
From there your machop evolves into machoke at level 28, and your machoke will evolve into Machamp by trading it.
I know nothing about egg moves and IVs and the like, so if I screwed up on any of this info, blame me. Otherwise, there ya go!