Is it possible to format the background of even and odd repeat region rows with different colors?

Hello William,
1. Select your repeating element (div or whatever container you are repeating)
2. Under Repeat Regions in the Data Bindings Panel expand your repeat region
3. Select $oddeven select Bind To: div.class and click the Bind button
This adds the following class to your container:

class="{{$oddeven}}"

$oddeven returns 0 for odd and 1 for even. So you can add by hand some text there, for example:

class="oddeven{{$oddeven}}"

This is going to assign class oddeven0 for the odd and oddeven1 for the even rows.
Then you can just define these two classes in your css:

.oddeven0 { 
  styles for odd row go here
}
.oddeven1 {
   styles for even row go here
}