Ok so your aquarium is 48in x 24in x 72in?

Digging deep in the brain recesses (and a quick google search for conversion from cu in to cu cm) the math should look something like this.

48x24x72=82944 cubic inches
1 cu in=16.387 cu cm
82944 cu in x 16.387 cu cm=1359203.33 cu cm
1 cu cm=0.001L
1389203.33 cu cm x 0.001 L=1359.20 L
1 L = 0.264 gal (liq)
1359.20 L x 0.264 gal=approx 359 gal (liq)

Someone please verify that math.

(And yeah, I know there's probably an easier way to do this but the last time I did this many conversions was sophomore physics)

The rule of thumb I go by for space is 10 gallons per frog. I would say you have more than enough room

As for plant help--in a tank that huge, I'd start w/ a "lemon-lime" Dracaena deremensis (I love the way these guys look), some ground cover type ferns (check Josh's Frogs for that), a couple of pothos, some broms or cryptanthus. And I'm out of plant suggestions--lots of the others have way more tank building experience so they should be able to give you much better plant advice.