A little help!

Okay so, being pretty knowledgeable in excel (I think) I am having a little trouble and im not sure if its just my brain is on overload or I may not know exactly what im doing please bear with me as I try to explain what i need to happen (In my head it sounds alot better)

I work for a company who has been doing things in the dark ages, and i have been tasked to bring them into the light. I've worked very hard to get what i can set up and pretty proud of it how ever im looking for my sheets to auto populate on what we call the inventory board. Each tab ass you can see on the bottom is for a different vendor we take product from and shows the cost of their product and how much we retail it for and the GP%.  (We have been doing this all by hands untill now) What i would like is in the section it says "Vendor" to have a drop down list of each vendor .. coke, pepsi etc etc and for it to automatically populate the cells that say invoice, charge, cash, retail. 

is this possible or am i just crazy? 

Thanks for any tips or suggestions.