1) Good for you.
2) Nobody, and I mean that literally, is gonna pay for 2.5k to 4k word chapters
3) As above since you won't be paid your collaborator won't be paid either hence, yes this is indeed a scam.
4) 5 days to write 6 chapters of obscene length, let's wager defaulting on that time frame results in loss of payment.
5) meh
6) Yes this is in fact a scam. Unreasonable stipulations requesting someone write your idea and only being paid when (if) you get paid. Had you said REGARDLESS of you getting paid or not this might have been believable, but you didn't thus, yes this is a scam.
Honestly if you're too busy to write your own story but aren't willing to pay regardless of its reception there's no other way to take this offer than you want free labor to make an implausible idea real.
Couple that with the fact your account is TWO HOURS OLD there's honestly no basis to trust you since you're too fuckin gutless to use your main account to be held accountable if this is in fact a scam.