Yes to both!
Using a linear motor instead of a steam catapult allows you to configure specific power during any point of the process. goombah99 mentions there's no shortage of steam, but newer carriers are moving away from needing steam to be generated, preferring to take power directly from their generators to the linear motors up top.
Could this be used for civilian airports? Most definitely! Its most likely cost prohibitive though, so unless you're someone leaving a major hub always near takeoff max weight (UPS/Fedex possibly?) or you're at an airport that has a very short runway or a very high altitude runway (both due to geography), it doesn't make sense financially.