If the spread width is too large then yes, the bought puts are irrelevant to your margin...other than the fact that they generally reduce your available margin by as much as their purchase price (which of course is small relative to a sold put).
Having more +P's than -P's is irrelevant to margin in the context of creating a put spread to reduce the margin on an otherwise naked put. The additional +P's may slightly reduce your total portfolio ∆ (if they're way OTM, not by much) but that's not something your broker cares about; that's just you managing your portfolio ∆.
It is VERY unlikely that a $200 +P bought against a $610 --with underlying at $6XX--will ever come close to reducing the margin requirements for your -P. Your broker should have a tool to calculate margin requirements, including what would happen if you sent XYZ trade on top of your existing positions. I would guess you need to be at least at $400 for the +P to materially reduce margin requirement on your $610 -P, but I'd also double check that before running out and buying a $400.
The big kicker is that the calculations get worse the farther ITM the -P is, so the more the underlying drops, the higher your margin requirements become. That's because your exposure to the underlying 100 shares remains the same (you owe 100x strike) but your exposure on the -P becomes greater (if you were put shares early, you essentially eat the negative value of the -P).
No, that falls into both the #1 and #2 notes from my earlier post.
1: You're creating a $650 wide put spread, which would normally require $65k margin for each spread. A naked $850 -P is probably only going to require ~$30-40k (total guess) of margin, so the $200's do you no good.
2: Because the +P's are closer in expiration than the -P's, your broker still sees your portfolio has having excess margin exposure, because on 3/6 when the +P's expire, you're back to a bunch of naked -Ps.
And, as noted above, the quantity difference is irrelevant for what you're trying to do. (More +P's may or may not be a benefit to other greeks, but that's another conversation)