I don't have this filter, but it looks like its rated for up to 175. I would think that would be enough flow.
As far as positioning, I think generally you want the in and out to be in different places so that its pulling flow across the entire tank. As far as positioning 2 intakes, or any powerhead I think the idea is that you want stuff moving in the same direction... or creating some kind of cyclical flow as appose to 2 things moving at each other.
I would just set it up and see how it looks. I think you want to have a gentle movement over the plants, and if it doesn't seem to be achieving that you can see what else you can add to improve.