Where do I find info regarding size of cake needed; i.e. "there will be 40 people at party"... When I checked another website, info seemed dated and said a 1"X2" piece of cake per person, is that how it should still be calculated?
Also info regarding pricing for family & friends- don't want to charge too much but don't want to lose $ either!

http://www.wilton.com/cakes/making-cakes/baking-wedding-cake-2-inch-pans.cfm

alot of people use this for calculating the servings

As far as pricing I really can't tell you because of the pricing varies depending on location. But a good place to start is cost of ingredients and the largest factor is your time.

In addition to the above chart, here is a link showing how to cut a cake to achieve those servings: http://cateritsimple.blogspot.com/search/label/cake%20comb

Here are pics of cut pieces of 1x2x4 servings, so you can see they are not "paper thin", which is what most people think when they hear "one inch": http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=1156785

When someone wants a cake to serve 40, what I would do is tell them, "A 6/10" tiered will serve 40-50, depending on how you cut it." I also describe a serving size as "about the size of a folded over peanut butter sandwich."

The chart in the link above is more for you to determine your pricing (and oh yeah it just HAPPENS to also give you an idea of ABOUT how many servings the customer will get).

I had a client want cake for 30 to 35 .. I told them "The 10" round serves about 35 if you cut them in standard serving sizes ...." She interrupted me and said, "Oh we better get a bigger cake, then!"