Not enough time for GPS lock for geo-tagging when taking a photo
I've found that if I'm using another app in the background that polls for location (e.g. latitude in Maps) I tend to get much more accurate geo-tags in photos. YMMV, but perhaps if you know you're going to be shooting photos you can open up Maps or similar first to start the process going.

WRT your battery life question, leaving maps open tends to destroy my battery in a few (5-7) hours (Dinc 1, known for horrible battery life anyway, even among android phones), especially if I'm shooting a number of photos. When I know I'm going to be using my phone in that manner I typically bring a second battery along, so that when I'm done I can still make calls.