60i is simply the video broadcasting format that 30p is put into- think of 60i in this case as a container. There will be 30p i.e. 30 progressive frames, but they'll be fit into 60 fields of interlaced video. So it will look like 30p to your eyes, but to the TV it will behave like 60i video.
Personally I prefer the look of 24p because it looks more cinematic and high end and 30p looks more like sports or home movies. But that can have its place as well. If you're looking for an overall primer on the HMC150 in terms of how it functions and why, I can't recommend this book highly enough:
You will hear many rave reviews on the book by Barry Green.
I own it, and read it all the way through when I bought it.
It's a marvelous reference for beginner and intermediate. I still refer to it months later.
It breaks everything down in actual, understandable english.
So, yes, it will have been worth it (even though it seems insane to pay that much for a small book)