ur budget?? 

hurm... i think u can get AP set with dat budget... maybe.. 
mine SGW 16gb White RM970 SME

Those except viber sounds like what my old nokia can do, excluding the gaming part too   
If budget 1k, you can choose from Galaxy W, HTC One V, Huawei Honor, and quite a few models from Sony(those lower end, something like Xperia mini, ray, neo etc etc). All these with with 8255/8255T Snapdragon chipset with Adreno 205, should be capable of doing what you asked for, all of them. All got wifi, got 3G (take note at front camera, some doesn't have it) etc etc. Viber, whatsapp can be supported by nearly all android devices, even in those with 600MHz proc speed. Battery might be a concern for you since you said you're going to use data. Based on technical spec, honor has the largest battery 1930mAH (+largest screen, 4" +highest resolution camera 8megapixel) but you better do research first, it comes down to whether you like the brand and how those parts perform. Go google la~ see how the screen and camera compare to those on other listed models