K-1 is not quicker than CR-1. It's longer (if you count time until getting GC) and more expensive.
Any hint of unofficial wedding, especially religious can void K-1. I would strongly suggest CR-1 route or do not play with religious wedding. Either way you're going to be separated for about 2 years, whichever route you choose. But in addition to 2 years overseas, with K-1 you'll have to add another 12-18 months to get GC. She'll get GC at least a year quicker with CR-1