It doesn't break saves? Awesome, though all my good saves were broken several updates back. How does the new crew system work? Did they add any more elements from campaign mode?
I did a single mission with my Muntasm II delivery system to the Mün and back, didn't take too many pictures though. Fairly routine banging mission on a more cratered Mün. Here's what I observed:
You can no longer end a flight directly from an escape menu, unless they hid it somewhere non-obvious. There is a rewind button during the launch sequence that lets you revert to an earlier time period (i.e. before you hit the button, or go back to the VAB).
Instead, when you want to end a flight, you have to go to the Space Center. Then, if the flight has landed safely on Kerbin, you have an additional button that recovers the craft and crew, then you can reassign them to new missions. There is still a terminate button, don't know if that has changed function or what that does to the crew.
The astronaut complex is always full of recruits of varying intelligence. You can recruit as many as you like, and then it fills up again. Pretty sure there is no effective limit, but I didn't read the documentation so what do I know? It also keeps track of everyone who has died...I don't have any on this save yet, but we will find out.
I figure that will be more important as campaign mode is built, but right now it just tracks your progress.
You can assign any kerbonauts from your astronaut complex to a flight on the launchpad or in the VAB. Also, you can place kerbonauts in any crew-carrying rocket part, so you can fill up your habitation module easily, for example, or you can pick which command pod is piloted before you get to the pad.
I have. It's straightforward and updating with Steam is soooo much better. However, when you transfer over you lose your old saves (at least I think) and you are locked into Steam-only from then on (can't get updates the old way). I don't see a reason not to transfer over, especially if you have to update anyways and eventually I think they are also going to migrate everyone over to Steam.
A KSP save is just a folder with two text documents describing your current missions: one "persistent" that has everything that has been autosaved, and another "quick" file that has your last quicksave, and then a folder with all your designs. I'm pretty sure if you copied your file from your old KSP folder into the KSP/Saves folder (or whatever it's called), you could continue your game on the Steam version.