I would take Rough Country right off your list. Their rear lift setup using only spacers is the main reason why. It's just not the way you want to lift the rear of your truck that much. They also don't powdercoat all the lift components; specifically the steering knuckles. So if you don't have them powdercoated or paint them yourself they will rust in no time and look terrible.
IMO a Zone kit is the best "bang for your buck" kit available right now. They provide a complete lift with good quality parts and rear coils to achieve the lift. Plus they still have a very good warranty should anything arise. A Zone 6" kit with 5" rear coils and Bilsteins at 2.1" is one of the most common setups I recommend. You end up with a total of 7" of lift and the truck will sit good and level.
BDS would the the step up from Zone if you have the money. They make the best box lifts for a 1500 IMO and provide the most options for the lift (ie. shocks, coilovers, etc.). Plus they have their "no fine print" warranty so if anything ever does happen, it will be replaced. Not to mention that they cover issues that may arise with the truck itself because of the lift.
I haven't had much experience with Superlift as it's simply not as common of a kit. However it looks to be a good, complete kit as well from what I've seen.
You will definitely need an alignment after the lift, no question. Any time any suspension modifications are done an alignment needs to be completed.
A lift definitely does affect handling. That's just how it is when you lift the truck up and throw some larger tires on it. You won't be taking corners as fast but that's about it. Really, if the truck is lifted right with quality components/shocks you will end up with a nicer ride than stock.
You can't get bump steer on a 1500 so no issues there.
Assuming you get new wheels/tires that have a more negative offset for a wider stance, then yes, you will lose a bit of turning radius. But it's really not that big of a deal.
The amount your fuel mileage will drop depends on a lot of things. What type and size of tire you end up going with, how you drive, tuning, etc. When I had my 1500 and put a 6" lift and 35's on it I lost around 2.0-2.5 mpg. Those numbers are fairly typical for guys running 35's. If you go to a larger tire (37's for example) then you might lose a little more.
On my 3500 the numbers were around the same, lost about 2.0 mpg going from stock to a 9" lift on 37's however my truck is fully tuned and the Cummins has a ton of power/torque so the milage drop isn't quite as bad.