How far away from the wall is a matter of personal preference. I install several lifts per week, and I ALWAYS tell folks to make your decision based on what you do 90% of the time. The axle thing comes up occaisionally, but until you actually see the columns standing in your shop, it's hard to get a pespective on how things look. But you don't want to move your whole lift over to accomodate the once in a while axle job, when you could back the car in instead!
As far as weight rating, you will probably be looking at a 10000lb lift since that seems to be the "buzzword" these days. However, Caveat Emptor applies here. All lifts are not created equal. There are several manufacturers that should be shot for the lifts they say are 10000lb capacity. Go with a reputable company and talk to clients in your area who already own the product. A 10K lift will lift most anything the average shop can throw on it.
If you choose to buy that internet lift, you could become part of the great Chinese Experiment. Notice how everyone on line has the "best quality lift"? Unfortunately I have had the experience of seeing the dejected look on the clients face when he realizes that the lift he just bought is really low quality. You should look for products that have the ALI/ETL or UL certification for lifts and are so labeled. And also find out who is going to service that lift for you when it breaks. I'll fix them in my area after the client calls the company and is told that "we don't do service there"
Here's a good way to look at your last issue. An asymmetric vehicle is a front wheel drive, where the entire drivetrain is in front of the windshield. This make the dashboard the center of gravity (the area that normally lines up with the lift columns). A symmetric vehicle is your SUV, Pickup, Van, etc. where you have a drivetrain that runs from front to rear. Typically, the center of gravity on these vehicles is the drivers seat, or farther back on crew cab duallys. Challenger Lift coined the phrase "Versymmetric" for their lift that is capable of doing both on the same lift. This give you the greates flexibility on how you load vahicles on your lift
Hope this helps,
Brian