It really depends on what you want it for but a few must haves would be the two you mention. Also things to consider would be a shower, generator, A/C, an inverter to run some ac appliances and even though having an oven is nice I'd prefer a microwave oven over a conventional. I have rarely used a conventional oven while camping in fact I think only once have I had the need to use one and that was for a turkey on Thanksgiving when the club decided to go out for the holiday and the only reason that occurred was that my wife as she put it, "I don't care where I have it but if we are going camping you better figure out cooking my turkey on Thanksgiving Day".
As to securement of the camper there are several ways this is done but the most common is from the frame in the front, there are frame attachments that will stick out from the side to secure it to. In the rear the rear bumper is the common point, there are small bung like attachments that are drilled into the side of the bumper that allow you to attach to. For your year truck don't use the Brophy rail mounts your bed is not made to hold it on, they don't make the beds like they used to. On my truck I still can use those and do but I wish I could run it from the frame but my huge side steps would block the mount point. The tiedowns are a form of a turnbuckle that locks it down to the bed, there are several types from preset to the new quick-release systems. The best thing to do on that decision is to take a look at the different systems and get a set within you budget.
On my truck I have the 8' bed and the camper is an eight foot model so it is almost contained completely inside the bed, I just have to remove the tailgate so I don't need an extension. If you get the longer campers then yes you will need an extension in order to be able to tow with it.
I have a dually F350 and since I opted for a shorter camper I have no need for airbags, I have considered it to bring the ride height back up but with the dual wheels I almost don't feel the camper back there and it weighs in at 1,800 lbs. On a 3/4 ton single wheel I would run air bags even with the camper I have so yes do the bags especially if you are also going to tow with it.
