First post, so hello everyone!

I'm completely self taught in Excel and have been scouring the internet for answers to a rather complicated project I've taken on. I'm hoping someone can help, I know Excel can make this happen!

Basically, our plumbing business winterizes houses each season. We have the same customers each year, and having been using a template that had been copied and reprinted for ages. It was messy, confusing and unnecessarily complicated.
I remade the template in Excel and then entered data so that each customer had a worksheet listing the specifics of draining their house. The constants on each sheet are the customers name, address, mobile, and date requested for winterization. What changes in each one is the items and quantities of items that we need to drain for their house. (Example: John Smith has 1 kitchen, 2 bathrooms, 4 hose bibbs. Mary Jane has 1 kitchen, 1 bathroom and 10 hose bibbs).

Problems thus far:

-I have created a separate worksheet that lists items and the prices we charge to drain them. I want to include a drop down list in the customers individual worksheet that lists these items and when selected, populates the cell next to it with a specific price. I have yet to figure out how to do this.

-Each year our prices change, so considering we have 300+ customers, it'd be great if all I'd have to do is adjust prices in the master list and all the worksheet are automatically updated. This has been some trouble figuring out.

BONUS QUESTION:
Is there a way that once a date is selected in a worksheet for opening the house, it can reference to some sort of master calender so we know how many requests we have per week?

Hopefully this was clear, I'd be grateful for any help you guys can provide. Thanks!