You can learn aperture priority mode copycat style - stick it in auto, press shutter halfway down and make a mental note of the shutter speed / aperture. Now switch modes and use those settings, if its wrong have a fiddle and try again.
I do this between aperture priority & full manual mode when I think the camera wont do what I want (probably because Im using the wrong metering mode) - by trial and error I find a way to get what I want.
I found it easier to get to grips with aperture priority by fixing the ISO (I use 200 most of the time), if its on auto it tends to chop and change a bit, which makes it hard (at first) to get a grip on the relationship between shutter & exposure.
Buy a 50mm f1.8 - £50 or so, gives you alot more freedom, especially if you are doing static stuff - flowers/indoor shots etc. As long as shutter speed is over 1/4 sec you should be fine.
What I need to work on is composition at the same time as the tech stuff, its easy to forget the artistic side while you are trying to do the tech stuff.
Far as batteries go, some say the cheap 7 day shop ones are fine, have no experience myself. I read on POTN that in the US a company called sterlingtek are well regarded, but I haven't found a UK reseller.