Tasker - How many Use it & How to use it on Android 4.2.2?

The title line pretty much says it, but I am trying to achieve the following on my phone using Tasker app. But I am unable to understand the whole design of the application.

1. I normally keep GPS and 3G switched off to save battery. But I would like to Switch GPS AND Data on when I open up apps like Foursquare, Facebook & Maps.

I would also like to turn off these, when I close any of these apps.

How would I achieve this automatically using Tasker?

2. I would like to create to create timed profiles on my phone. I know this is achievable through Tasker, but cannot figure out how.

Has anyone tried to achieve this using a simple step by step guide on Android 4.2.2 ? since app looks very different compared to its versions on Gingerbread.