Confusion on multiple design resource files in Android

Question

I'm trying to accomplish whats written HERE on supporting multiple screen sizes, I understood that every design in the app should be in 3 sizes.
1. The designer asked the 3 sizes he should design for, he already created designs in 1 size which is 480x800.. What are the other 2?
2. My .apk file is 5 mb big with only the designs of 1 size (480x800).. So when I add the 2 other the .apk will become huge.. How do I avoid this?

Answer 1

Obviously you need to compress the files to a suitable size and implement the look and feel in code/xml.

Besides that if you still run out of room you could create multiple application for different devices with a whole bunch of disadvantages in terms of market presence.