I am building a 'add-on' desk/shelf for a friend this week end and using one of this size and one 72" long. Neither have the sizes they are posted as !!!!!!! it is raining now so I am not able to go out to put an exact size on it ( or either of them ) but it is less then 3/4" thick as well as less in width ... length is very close to correct ! yes a surprise to me ! I hope this helps You .
Each board weighs approximately 11.3lbs
No, there is not.
a very good 'rule of thumb' . if it is more then 11.5 inches wide .. it is many pieces glued together ! this is NOT always bad as many times this 'CAN' be stronger as well as less impurities in the finish ! I use this type of pre-made sizes because it would take me an extra day or more to make my own this size by cutting and gluing and clamping. then trimming and sanding to get the same results. if you go to buy this type , be sure to check both sides as well as the edges for dings of knot holes .