1. You are asking a question, so you should be posting it in the question and answer forum and not the DEVELOPMENT forum, which is mainly for development. So you are posting it in the correct forum.
2. You won't lose YouTube and Google Play. I believe the builds here already come with them. If not then it is a simple matter of installing gapps. Also, the play store isn't blocked in China.
3. Battery life is subjective and depends on how you use your phone. It made no difference with mine but it is a matter of what apps you run and how often you run them. Everybody's usage pattern is different so you can't use others' opinions on battery life as a gauge for your own.
Current - LG Nexus 5
, franco.Kernel r11, Cataclysm ROM
Current Tablet - Ainol Novo 7 Aurora II
, CyanogenMod 10.1 Unofficial
Sony Ericsson Xperia X10, CyanogenMod 7.2 Unofficial, spoilt battery
Sony Ericsson Xperia arc S, Stock 4.1.B.0.587, lost back cover, spoilt microUSB port
HTC HD2, NexusHD CM10.2
Apple iPad 3 - iOS 6.0 Jailbroken
Minimalistic Holo Blue Whatsapp+ Theme
Nexus One boot animation for Nexus 5
How to Change DPI?