If I wanted to create a publicly facing database for purposes of connecting it to a client MS Word or Open Office Writer installation, would this be considered a dangerous security practice? What if I have set access permissions to various tables in the database?
It's generally considered bad practice to have a public facing DB server. Does it have to be a DB?
My personal opinion is this is a trade-off. How complicated would it be for you to set up a more secure public interface, versus how dangerous it is for you to risk the DB attacked and/or compromised. And of course it depends on how good you are at hardening the relevant server.
For a small shop - i would probably do it. A big company can hardly afford the risk.
Regardless of the size of the company, a Firewall in front of the server is a necessity nowdays.
Yes that would be a bad idea. If the system is connected directly to the public internet then an attacker can (and will) start brute forcing their way into the account starting with the sa account. Once they've broken the sa account (and it is just a matter of time) they will be able to reconfigure the server to allow them to install whatever they want on the machine and jump from there to the rest of the network.
Once this happens anything on the network is readable to them, usually pretty quickly.