yes of course but blower coolers have always been single fan. The benefit is hot air doesn't flow into the case but rather gets exhausted through the rear. There's no harm for sure if manufacturers should one day decide to slip in a 2nd fan into blower coolers though.
Given the choice, i take a blower cooler cos of its looks and it also keeps the pcb shielded from any possible damage.
Since one has a reference card, it would be logical to get a aio fitted with a shroud.
for non-ref, usually it comes with heatsinks on vrms so G10 will be suitable.
There's no real need to cool the vrams. Again, no harm if one puts heatsinks or fans on it. But it's not necessary. Just like fans on HDD/SSD isn't a must.
The G10 isn't a bad product. A lot of folks criticise it cos they mainly come from the AMD Ref side, which uses thermal pads from the shroud the cool the vrms on the right and the left. I think NZXT could have done better in putting more info on those cards.
If anyone had tried the G10 on a non ref 290, most likely they would have noticed heatsinks on the vrms and cooling would never be a problem.
In short, if u have a ref AMD, use the HG10 for less hassle. If u insist on the G10, fit the heatsinks on the vrms.