Second question is about pywallet, is it really safe to use it? i mean it sounds like it could be stealing your keys easily. Like what's the way of using pywallet safely?
Assuming software is compromised is a good default. The easiest way to be absolutely sure pywallet (or any other software for that matter) doesn't upload any data, is by using it on a system without internet access. Wipe the system when you're done.