Default Questions About Kit Kat

Hello

Basically I'm going to be out of the country in 2 weeks time and did not want to update in case something got borked and I'd be without certain stuff while away. Essentially I've got the viper audio mod on a stock 4.3 rom which is now "unrooted" so certain other apps can work properly. Viper still works fine on this unrooted phone though.

In relation to Kit Kat I have a few questions so I know whether it's worth me upgrading now.

Can I downgrade back to 4.3 on a knox voided boot-loader phone?

Does the stock camera or the new google camera app allow you to save to the SD?

Does viper4android work on it?

With this SD business, can I still download stuff onto it and/or copy stuff from a usb stick connected to my phone onto the SD?

That's it for now
Current Devices: Samsung Galaxy Note II, LG Nexus 4

Previous Devices: HTC Wizard, HTC Kaiser, HTC Touch Pro 2, HTC Desire Z, iPhone 3G, HTC Mozart, HTC EVO 3D, HTC Trophy, iPhone 4, HTC One S, iPhone 4S