The Marksman DLC is NOT a patch. It is additional "for sale" content. The weapons it will include (some DMRs and sniper rifles) will not be usable if you don't pay (its $4.99 or $5.99 I think) but the engine modifications for wind, bipods/weapon resting will be part of the game for every one.
My group has no problem hitting targets at range. We have some recorded 2000+ meter shots on Youtube. If you have decent internet (read that: 10MB+ up and down) you shouldn't have any problems with long range shooting due to lag.
DLCs and mini-expansions that cost additional money are not unique to Arma 3. These companies are not running charities, they don't own you free extra content.
VooDoo, if you enjoy wide open military style shooters, this is the best one there has ever been. 270+ sq.km. of room to maneuver, combined arms combat with Air, armor, mechanized and infantry, good weapon modeling, damage modeling. Whats not to like? Try it out.
There are HUGE milsim groups if you want to do max realism coop and some pvp stuff, there is Wasteland if you want more shooting and less waiting for orders and less walter mitty wannabes. Breaking Point if you want zombie apocalypse pvp. King of the Hill for team based sector control. There are a lot of options with Arma 3.