As for the jar to alx... You dont need that. Download it (the jar not the jad) to your computer. Transfer it to your phone (either internal memory or media card). Disconnect from the computer. Go to your media. Hit the menu button. Select to explore. Find the jar file (should be where you put it! ) Select it and press down on the trackball. It'll install the program. Dont need to use OTA.
Read up on this to make backups if you need, or you can always save the jar file and use it again.
Why do you need backups? Because you'll reinstall the OS on the phone a few times, and you'll kill the phone a few times and what not. Helps if you have everything backed up... Sometimes it gets a little hard to find everything over again. What? You will never reinstall the OS? That means that you aren't using the phone enough!
As for free internet... You can download Opera Mini and it probably holds more info per page than a regular browser...
But if you use it, it'll use data and there is no way getting around paying for it. Watch what you download. Here State side we have to pay per kb. Paying per page is a new one to me and not sure how that'll pan out. I'm sure someone with more experience in this particular line will be along shortly and clue you into how this works or how to squeeze more out of the deal... or to tell you that it's not possible.
Hope that helps. Good luck. BTW. If you find out how to get data to your phone without paying for it please take the time to clue us in on the secret! That's the holy grail!