I can answer a few of those questions hopefully well enough to help you decide
1.) Yes, in fact it exports in a format Construct 2 will not be able to open, and does some tricks to make code hard to reverse-engineer.
2.) It does provide you with estimates of the memory usage of your game as you're making it, and I think you can load and unload images per each layout (level). As for CPU usage there is handy debug and possibly also profiling tools to help you optimize.
3.) Yes, I'm not sure if there's tutorials or examples around, but I did this for Insanity's Blade for future localization capabilities. I think I loaded the text straight into a variable with the AJAX plugin.
4.) Yes, these can be done as functions or by activating/deactivating groups. You can include event sheets inside of other sheets too.
5.) Not sure about this one, but you can use 9-patch to do rounded boxes that scale to different sizes!
6.) I'd say definitely, but can't remember that example. You can probably do it easy with Spriter too but it should work with just sprites + events.
7.) Yes, that's pretty straight-forward eventing.
8.) Not too certain I can answer this one, but you can create and import event sheets pretty freely once you have a full version of C2.
Hope that helps!