just wondering how much work i'd have to do.

It takes about 3 minutes to install. No joke. There are two pegs that hold the original grill into place, pull both of those out and the old grill slides up and out and the new one slides down and in. Then just put the two pegs back in and you're DONE! That's it.

im afraid someone would want to steal it after it is installed. is that possible from the front of the xb? or would they have to pop the hood open?

It installs just as if it were the factory grill that comes with the car. It uses the exsisting "pegs" for the factory grill and takes about 3-5 minutes for installation. I am quite happy with mine and it adds a great front impression.

Carson Scion has it for about $275 or $295 I think.(newscionparts.com)
That is the best price I found for a trusting place to buy from.

They'd have to pop your hood. It slides over two "posts". The pins just hold it in place.