Dollar General $5/$25 Coupon Info

I just started using the Dollar General $5/$25 coupons last month. I've done this 4-5 times now and here's what I've learned.

1) DO NOT shop at the S. County store on Tesson next to Old Navy (near Sams). Long story, but in 2+ years of couponing, I've never been in a more "coupon unfriendly" store - and I mean of any stores not just Dollar General!!!
2) Ask the cashier to key in the coupon code, not scan it. From experience, when scanned it will beep like the coupon has been accepted but nothing will be deducted. But for some reason keying in the code works every time.
3) Most stores will accept the $5/$25 coupon before other coupons, however I've been told by 1 cashier that they can't use it with any other coupon and another cashier that it is supposed to be $25 subtotal after all other coupons are deducted. However, both times the manager let me use it.
4)My Dollar General will not adjust down the value of a manufacturer coupon, so you can't get a free item if the coupon value is higher than the item price.
5) The $5/$25 deducts a percent from all the items you've purchased. Not a big deal except for #4 above. If you have a manufacturer coupon that makes an item free at regular price, it won't work with the $5/$25 coupon.