would it damage the bike to ride it on sidewalks at all?
Yes it will... when you plow into a side of a car at 20 mph....
16 miles one way ON A SIDEWALK? Oh my... There are two mutually exclusive ways to ride on a sidewalk: fast or safe. Not both. Either you'll take forever to get there or you'll be putting yourself in danger at every intersection. Unless your sidewalks have almost no driveways or other intersections, do yourself a favour... ride on the road. An ancient lady on an ancient cruiser looks fine on the sidewalk. But Specialized Tarmac on a sidewalk looks way too sad.... sort of like a yacht in a swimming pool...
Even if you have to make your trip a couple of miles longer to bypass nasty roads in favour of less trafficked streets, it'll still be much faster than a sidewalk.
Here is a guide to safe road riding.
Also, what are the chances of my bike being vandalized while in the employee parking lot, i've never heard of it happening where i work (very high end resort hotel) but im just wondering if anyone ever vandalizes bikes because they're pricey.
Who knows? *shrug* We don't really know your area. The fact that you've never heard about it may mean that it's not likely to happen, or that there have been no bikes there before to vandalize, or that you're misinformed. Interesting, though, that you're worried about vandalism more than theft. While vandalism does happen, theft is more prevalent, and is in general worse since it leaves you with no bike at all. Invest in a good U-lock or chain lock, be sure to lock the frame (not just a wheel!) and lock up or bring with you anything that's quick-release. Better yet, see if you can keep your bike in a safe place inside (e.g. your office).