Since you are in Michigan, I am going to throw this into the air...
Snowboards.net is owned and operated by Summit Sports which is a Michigan based business. There are 6 Summit Sports stores throughout Michigan and 1 Don Thomas Sport Haus in Birmingham.
With that said, we are low on our current stock of snowboards so I can't link you to good ones for her size. For her weight, a 138-143 are the perfect sizes for her. 145 is a bit large for her. I would normally say it will be fine, but knowing the slope conditions in Michigan (lots of ice and hardpack, very rare powder days), she will have some difficulty learning on it. Once she does learn though, she should be able to ride it. Trust me though, the moment she steps onto a smaller board, she will definitely notice the difference.
The Roxy Ollie Pop is an excellent board especially with the BTX tech which will own the icey conditions that we are so used to here. 138-140 sized boards are hard to find. The best luck you will have with those sizes will be under girls boards rather than adults, but that is going to really limit the choices as kids' boards are usually built to be more forgiving.
Your girl is indeed rather light for her height lol. Anyway, she'll be able to ride the 145. It'll just take a little more effort in the learning department. If you can find any in a smaller size, that would be great.
As for her bindings, she will normally fall under mediums. Make sure you check the manufacturer's sizing charts though because they do fluctuate between brands. Here are some good ones that we still have in stock:
Ride DVa Womens Snowboard Bindings 2010
Flow Essence Womens Snowboard Bindings 2010
Burton Lexa Womens Snowboard Bindings 2010