I'm just gonna give some basic advice,
The range depends on what type of replay do you want, for madmans i think the default engage distance is best, But for things like stylish decaps and such, 150-180 engage distance is good.
There is only 2 gravity's that i think should be used for replays. Default, and i think its -21 (I havent used higher gravity in a while so correct me if i am wrong)
And the best thing for dm's is build alot of momentum and aim for the joints.