Sorry I didn't anything past "Heavily considering the purchase of Streetdeck... " before you even think about it or spend too much time familiarize yourself with these two threads:
There might be (don't hold your breath) an annoucment made within the next week or two that will hopefully clear things up on SD's future.
As it stands, SD is nice, not great, there are several flaws and a alot to be desired, but is great as is for starters.
-1-search for "-testmode" and associated threads will tell you how to bypass this. I use this and the "-testmode" mouse click bypass and use my SD to the full extent
-2--ummm yeah again wait for SD future as no one knows the answer
-4-no you can run in Developer Mode on desktop, but can run SD fully (like it was an install) for 30 days, Dev Mode runs forever, just looks like Dev mode
hope this helps.