Alright! If I get the Day-Z Standalone, can I get the wasteland mod??
No. There are no mods as such for SA and never will be. wasteland is a mod for either Arma 2 or 3 only. Like i basically said above if you want lots of mods/content then Arma 2. If you want the best looking game out of the Arma series to date, and limited content then go for Arma 3.