LCDs in general, and Samsungs IME particularly, tend to be fairly bright. I usually have to turn my brightness down, whereas with CRTs I usually had to turn it up.
Also, the Samsung's auto-detect mode actually does a fairly good job at getting the settings to a decent level. You may want to fine-tune from there, but it's a really good start.
Yeah, I sold TVs for a while myself, and it's measured from corner to corner of the screen. Well, actually, I suspect it's corner to corner of the opening in the case, but it's pretty much the same.
As for the increased size, I only have a guess. CRTs are slightly convex, whereas LCDs and flatscreen TVs are, well, flat. I suspect that while the diagonal is measured the same, the curvature of the CRT actually decreases the viewing area even when looking straight on. It's the same reason the viewing angle of a flatscreen is so much greater, I think. So when you switch from CRT to LCD, it seems like you're getting more space, when you're not.
Also, resolution plays into it a bit - but I'm assuming that the LCD is being displayed at the same resolution as the CRT. I know I definitely noticed it, and I was running at the same resolution. I've heard a lot of customers make similar remarks when consumer flatscreen TVs were relatively new. That is, once I spent half an hour on the phone with them telling them how to hook them up.