Judging by the three pages of posts this isn't going to be over anytime soon, may I suggest... Reading the labels on any and all herbicides, pesticides, fertilizers, seeds, and most anything that you are about to put down, read the label and the application statement, read how to put it down, when, what it affects and what its side effects are... In short, learn what you are doing while you are doing it, that will at least help keep the learning curve down to the essentials, and believe me it's still plenty long so you won't get bored anytime soon, please read that and many of the other things...
As a rule, when two statements contradict themselves, it is generally safe to ignore that until further evidence presents itself.
As a rule, when the majority of statements lean in one direction, that tends to be the truth.
One thing I can tell you...
Weed killer and grass seed interfere with each other, specifically the weed killer will keep grass seed from germinating.
You can try it like I used to do, and get smart and realize the interference only lasts 30 days and ...
You know, throw one down now and then if I wait 30 days I can put the other one down, yeah that's it!
Until you make a mistake, anyway.
Or you can do what I learned to do in my later years.
Fight Weeds in the Spring.
Seed in the Fall.
No more interference.
Last but not least, start learning how to cut your grass high.