Width and Length both do matter...
With more width, you have more surface area in the water at a time.
A beginning rider does put more weight in the rear, but more advanced riders start to center out their weight more. and ride much more even.
The sandal (Strap-on) bindings are "OkaY" they will get you through your basics cutting the wake, in learning to jump the wake, and basic 180 spins. But, after that, they are pretty worthless. I have an OLD-skool Hyperlite skurfboard that has sandal bindings on it. I ride it from time to time just for fun.
With your height and weight, you are probably better off starting on the 142. I am only 170lbs, and I ride a 142 as well.
Wakeworld has a board wizard that if you put in what you want it will give you the boards that suit you. You can use to get a general idea of what sizes and widths you should look into. Due to your previous learning curve with skiing, I would also suggest getting a beginner/intermediate board. Maybe something with Two molded fins and a removable center fin on each end. This will allow it to be really stiff with the center fin for learning, and when you start to get more advanced, you just pop that one out and it gives you a much more loose feeling. Also, the center fins will help is you end up in some choppier water.
Also, the rocker type makes a big difference as well. Most beginners start off with a Continuous rocker since it is more predictable and has a much more steady “POP” each time you hit the wake. It is better for learning. A 3-stage rocker has much more pop, but it is inconsistent if you aren’t adjusted to it. A lot of boards use hybrid style rockers now. They pretty much fall in the Continuous rocker side of the spectrum.
One last thing is the year of the board. Now, I am not saying go buy a 2009 model board, but wakeboarding has come a very long way in the past ten years. Between shapes, nose and tails designs, rocker types, and the major component - materials, things have gotten much more advanced. I have demoed a few newer boards and they ride much nice than mine. I just haven’t been able to allow myself to spend the money on them. I have ridden a ’08 Axis and that thing was really smooth on the water. I also demoed a ’09 S4. It was very slick but had some nice pop.
Well, hope this helps in your hunt for a good board. If you don’t plan on getting really into the sport (Most people start that way and then get hooked), then any regular board should get you going. But, one thing I tell everyone that wants to try the sport out, be patient. Don’t rush to buy anything. A lot of places now will let you demo a lot of gear before you buy it. So, I suggest looking around to see if that is a possibility for you.
Buying your first board is a big commitment than people think. Not knowing anything and then just buying something random, can either make or break the sport for you.
Good luck… Let us know how things turn out.