OS 10.5 - run script when 1) internet is connected 2) login/logout/wake 4) some app is launched

Hello,

To track my computer in case my laptop is stolen, I am currently running a bash script to send hostname, ip, and cam capture image to my email every 5 minutes using cron.

I believe this helps when I lose my laptop, but I want to send an email not only in timed manner but also in some critical incidents.

i am thinking three cases:

1) internet is connected
2) login/logout/wakeup
3) some app (safari, etc) is launched.

I searched web, and found this:
2c) wakeup case can be done by SleepWatcher

However, I couldn't find other cases, and i prefer non-daemon approach (sleepwatcher will definitely use some memory.). I hope that i can do it with scripting languages, such as applescript or bash script. Please let me know if you know any of three cases.

Thank you.