If you want to keep your email safe then ask your ISP if they support secure POP, which they should. Then it is a simple config change in your e-mail client.

However, as other have pointed out, e-mail is just plane insecure. If you want to sure it up a bit there are encryption programs (OpenPGP, etc) but they require that each user has the program yadda yadda... and there is very little preventing that email from being forwarded once decrypted. You can also get a personal certificate from someone like registerfly.com which will allow outlook to encrypt email.

But banking and shopping online, as long as you see the little padlock, is very very safe.

Wireless at home is a tricky beast. The only strong protection is WPA. WEP (on older models) and MAC filtering are 100% worthless. In other threads others have pointed out "yeah, but who is going to bother when there are tons of open APs around?".... anyone 12 year old with free software is who!
Turn on WPA on your router and you are golden (of course Steve Gibson would suggest a 63bit password from www.grc.com/pass... which is what I do and keep it on a network share on my lan and on a usb stick)