I would say confidently you will get into your beer on tap and want more than two.
I hear a lot those fridges they sell on eBay are cheap asian ones that aren't great quality. I'd personally pay a bit more for the same setup from a trusted Aussie brew store for peace of mind.
And have a think about where you are going to put it and room temp, those towers heat up and the first pour can be no fun. Building a small fan blower up the tower will help eliminate that and there is plenty of info and peoples set ups online to view. Some have the tank strapped to the back of the unit too but that limits you to a small 2.3kg bottle and means the unit sits a fair way away from the wall. Otherwise you need to stand the tank next to the fridge.
Can you tell I'm not a huge fan of them yet?