I'll try to keep it short:
-You can downgrade with every version but the last one (which is 11.0, the last downgradeable firmware is 10.7).
-There has been a lot of new released entrypoints:
http://wiki.gbatemp.net/wiki/List_of_3DS_homebrew#Exploits
-A new hack called arm9loaderhax (A9LH) which runs at boot time, similar to BootMii for the Wii, so it even works if your NAND is bricked, it doesn't require Emunand. Thought the installation can be long and slightly risky, but the guides should keep you safe.
-Aside from googling for game's CIAs, now you can use tickets to download/install games directly from Nintendo's servers, applications such as freeShop, CIAngel and Shameless work with this.
That's uhh pretty much it, the most commonly used CFW is Luma, since rxTools stopped being updated (Though somebody else is trying to revive rxTools, but I don't know how they're doing).