Android build problem

Hello comm unity I created some simple app and on PC build it works perfectly. But when after Build & Install it on my old Android HTC, it not propperly works.

And I got some question:

First of all, how can I get error log on Android devices (developer build doesn't help much)?

Tell me do I need to use Android manifest in all Android apps? Or may be I need some Android plugins, if I making the Android build? Or may be the path to Rescources folder has to be changed?