You can get full black theme by flashing certain pack through CWM. You need to root first.
There's no way to get 8MP 16:9 (around 3764 x 2118 I presume). It needs to lengthen the max width, which is 3264.
You can set your own preset to make "rock". There are plenty of samples on the web.
Transfering app to external sdcard will drain more battery as it needs to actively read / write data to it.