It varies...and varies GREATLY...depending on where you are.
In some states with not so good laws about personal protection (and the general similar public opinion that often accompanies those laws)...its never going to end well for anybody, which is a sad state of affairs all around.
In other states, such as TN for example (I live in TN)...It may not be a big deal at all.
As for the corporate decision on whether to fire you or not...it just depends on where you work and if you have any protection on a state level (workers rights)
I'm a truck driver...the company I drive for does not have any policies that say I cannot carry my pistol, but if I were to have to use it...and the media got a hold of it (as they always do)....then the company's public image is at stake and they go into "self preservation mode".
I really don't care about their image...I'm locked and loaded 24/7/365...its a cruel world out there...full of all kinds of deranged individuals.
My Glock 36...dynamite does come in small packages.
As far as a "right to shoot"...Yes, we have the right (in most states)...many states have what is often called a "Castle Doctrine"...and the text of it varies from state to state...but in TN it basically says I have the right to use deadly force to defend myself pretty much anywhere (anywhere I have a legal "right" to be)...work, Wal-Mart, gas station..anywhere.
I'm pretty well read on most states (I have to be, I travel them all)...they vary too much to give any kind of blanket opinion.