Akward? hah more like normal mantis behavior. Most Mantises prefer to perch up on something and avoid the ground. Perhaps you might want to try getting a screen/mesh cage. I like them because they are easy for the mantis to cling to so they don't just hang on the celling but will skitter along the walls a lot more since it is easy for them to grip. The grip also allows crickets and other prey items to in turn easily crawl up to the mantis. Makes feeding a breeze.
The activity of hunting can also very between mantis species, gender, and even individual personality. I keep mostly Chinese mantises and most are pretty active in hunting, especially full grown females. I have a 50/60 gallon tall screen cage and had one female who would race from the top of it down to the bottom and around the cage to catch crickets. She had no patience for sitting and waiting for her dinner to come to her.
As for blue bottle flies, you might be able to get some from an exotic pet store (if you have any around you) but your best bet would probably be to order some off the internet.
