I highly recommend buying a Bo-wrench; you really need some help trying to straighten out any bowed boards since the t-wood is so dense. Also, leave a good gap between boards. When I installed mine, I didn't leave enough of a gap and ran out of time to seal it before the rainy season (Seattle) began. Probably because of that, the boards swelled and closed the gap. Last summer I ended up taking all the boards up and re-spacing!

Tigerwood is pretty much hard as Ipe and Cumaru so I think you are fine with 16" span. Check your local building code when you are ready to pull your permit, they may have a say in that. I'm a fan of 12" joists simply becuase of less give (very solid surface) and less waste, and with exotics, I'd rather spend a little more on the framing than paying for more Tigerwood than you are going to use...given that they are typically sold in 2 ft. increments and you have to figure 15% waste on diagonal vs. normal 10%.

Agreed on spacing, give it plenty of airflow, maybe 3/16" or 1/4" spacing for good stability.

Also, since Tigerwood has varied figuring, you may want to lay your boards out first to make sure you like the patterning. Some boards are very figured, some not so much. Good to lay it out in advance so it's even...no dead spots where it's too figured or too plain.

Also, find out exactly which Penofin they used to pre-finish with. Keep some extra handy in case you need to touch up spots or do an extra coat after installation.