I don't think they have to rule out sex. I'm guessing they can have sex all like as long as they don't have kids.Yea, I understand that but what makes you think it won't be a long term marriage? And income disparity is bound to happen here. His vetting process doesn't look too strict [since he literally only wants someone who will play wife in front of his parents]. I'm not sure where he's from but it definitely doesn't hurt to be aware of the laws in one's region regardless. And he didn't mention a contract at all though, so I think that he's expecting to 'surprise' her once she is already committed.
I don't think he's looking for a Muslim wife...but if he is, I'd imagine that it would be almost impossible to find a normal Muslim woman that would be okay with not having kids (because the parental/cultural pressure on her side would push her to reproduce also). Thus, he'd have to look elsewhere (non-religious women) if he perceives marriage as a requirement.
As for the not cheating thing, nah...it's not as simple as that. If the woman was too religious to cheat, I assume that she'd be too religious to engage in pre-marital intercourse as well. That means she would be signing up to be a virgin for the rest of her life (that's some monk type sh!t). The average woman has biological needs that need to be met and...so, he'd have to luck out with either an ace, a low libido woman, or a woman with strong willpower who doesn't mind the terms of such a marriage. Again, highly unlikely.