Most board manufacturers and generic calculators place me on a 168. I ride a 162 freestyle board for all mountain and freeride. Not ideal I know.
Prime, you are comparing apples and oranges; i.e. you are using your old stance settings on a different board.
1) According to product description the Ride Timeless is a Highspeed freeride board. Whereas the Atomic Hatchet is a freestyle board.
Excerpt: Deemed the ultimate freeriding machine, the Timeless is Ride's undaunted model.
Atomic Hatchet Snowboard - 2006 BCS from Backcountry.com
Excerpt: The solid freestyle performance of the Hatchet Snowboard has made it the best-selling snowboard in the Atomic line worldwide.
So freeride boards are usually stiffer and directional. While freestyle boards are usually more flexible and either true twin or directional twin. This is not an absolute but a good generalization.
Explanation of true twin, dir twin and directional.
For snowboards what does "true twin" mean? Is it the same as dual directional? - Yahoo! Answers
2) When researching/learning how to ride your board you need to look at your weight, ability, stance and shoe size. There are probably other factors I'm missing but this should give you a start.
For example, I currently weight 180 (but float between 180 and 165), Intermediate skill, my stance varies (on conditions, terrain and board) and wear size 9 Burton Sabbath boots. On my 155 NS SL; I ride duck 18, -15 with a 22.5 stance width. On my old 162 Morrow Blaze; I ride forward 21, 12 with a 20.0 stance.
3) Here is a link to help find your stance.
Hope this helps - Nito