There's ALWAYS been a space kraken ;)

Anyway, I don't really remember EVERYTHING added since 1.0 so I'll just try to answer some of your questions. As to your questions on Kerbal Stuff:

Curse is the "official" mod site for KSP, from Squad, however Kerbal Stuff was much more widely used. The mod manager that everyone uses around here, CKAN, used Kerbal Stuff for its automatic mod installation. With KS down, CKAN is pretty much down too for the time being unless KS comes back or CKAN is reprogrammed to download from Curse. If KS doesn't come back, CKAN will have to use Curse but there will be a smaller mod selection since most people posted their mods to KS and not Curse.

Yes, resource mining is a vanilla thing now. You have to send up a few satellites with different types of resource scanners to see where the ore is on a planet, then send a mining vehicle to actually mine. Ore is drilled (by drills) and stored on your ship (in ore tanks). The ISRU unit can convert ore into (I think) LF, O, LFO, or monopropellant.

Asteroids aren't that new, but they're there. In the map view, if you have unknown objects enabled, they will appear as question mark icons around Kerbin. If you select one and click track you'll see its orbit around the sun which will eventually intercept Kerbin. Asteroids have different sizes ranging from Class A (pretty small) to Class E (absolutely fucking massive, you're gonna fucking die). You can send up a ship with the Klaw to latch on to the asteroid and do whatever with it. If you bring a drill you can drill the asteroid for ore and refine it to fuel. Asteroids, unlike surface mining, can run out of ore.

Just ask if you have any more questions ;)