Hey, way too nice of a truck to be plowing with, eh?
Anyway, go with at least a 8' straight blade or a 8.5 V (better choice). You have a heavy weight truck to start off with so pushing would be better than with a pickup.
How are you going to transport the salt? Do you have barndoors or tailgate? With a tailgate, you still wouldn't be able to lift the rear glass to get to your salt or spreader. I have a Buyers 600lb cap. spreader (simple design), however, I think that it would be almost impossible to modify it to fit my Suburban (1975 3/4T) and still have it perform adequately. I have seen a small (can't remember brand) yellow reciever mount spreader that looks to only hold about 200lbs and is very low mounted. Maybe thats what you are planning on.
What is this rear air lift that you have?
Don't worry about damage to the front end. As long as you don't beat it, it will be fine. It just worries me that you are plowing with a $38,000.00 truck.
Just get a ciggarette lighter plug magnet mount beacon and you will be fine. (Starsky and Hutch) Unless your a firecop or whatever, stay away from those big hideous light machines.
Also, unless you do a lot of sidewalk work, skip the rack and blower as there is more money in plowing.
Good Luck, and dont wreck that nice rig!!!