Need help with dates in a form

I will preface this post with the fact that I use, PS, ID, way more then I have ever used LiveCycle. I have recently been asked to develop a form with LiveCycle for the office. Way out of my comfort zone!
The form is a basic invoice for a guest house,

Here is what I want to do

I want to put an arrival date with calendar
Departure date with calendar
Then a box with total number of days stayed, have it calculate based on the calendars days stayed and then put it in the box, next to the box I can put the price per day and have it figure it out.

I need to know a few things and your help is appreciated

1- First where can I learn LiveCycle basics free online. I need to understand a little better how things work. I noted some codes that people posted online saying something like what I need above, but how do I add them? Do the codes go in a text box or where? I need to learn LiveCycle basics 101 and quick! Is it through a caption?

2- Any ideas or sample of something similar to what I need above that I can work with for a bit to learn?

Thanks for your help