Apk protection (or how to discourage the desire to watch your code)?

Question

Android

I read a lot about protection, but I 100% agree that any protection can be bypassed to have a current desire, but you can make it so that those who already do it do it for a long time ....
1. ProGuard is a great thing, but most of the material that I found on 2011 I would like something new on this topic (most likely I was looking crookedly) and is it worth using?
2. In string.xml I have facebook id, ad unit id. Is it safe and if not what are the options?
3. what do you think about apk protection?

Answer 1

1. Proguard is a minifier, not an obfuscator. It just reduces the size, removes the excess. Reading is harder, but not by much.
2. Nothing special can be done with these IDs. The token from the official client of VK walks on the Internet.
3. There are protections written by professionals, from Licel, for example. Do not write protection on your knee.