1. Chromebook can't be used unless tethered to the Internet (although I think I read somewhere that they can be used offline).
For the most part they do like to be online yes. But there are some apps you can use off line as well. PLUS many Chromebooks run a limited amount of both android and linux software.
2. The operating system is Chrome OS. Should there be any concern with privacy since some folks are afraid of using their browser?
I know of nobody afraid of the browser but as with all operating systems security in our criminal laced world is a concern.. I use chrome books a lot and I'll comment more at the end.
3. Are chromebooks inherently less prone to malware attacks?
I do not think so but they have a way to deal with it.
4. Do chromebooks have hard drives, similar to regular computers?
Mine have small SSDs. Plus I have a micro SD card in the slot and if I need I can plug in an external HD (They make 2TB thumb drives now days)
5. If you use one, do you have anything to add?
When I got my first Chrome book I headed to a nearby Denny's that had a very good high speed WI-FI. I've set up many Windows machines and was expecting to have both breakfast and lunch before i got 'er done.
Set up my Windows machine and pressed Power. Took the Chromebook out of the box nd did likewise... I was on line and browsing with the Chrome book before the windows machine was booted up and running.
Now: the malware story:
ONe restaurant I have eaten at has (usually) customer wi-fi. if that's not working the city has Wi-Fi as well. but it's been hacked, Both of my Chromewbooks got bit. I was able to get to Settings, advanced, power wash and WHAM. just like that (Took abou 1-2 minutes) I was back to "Taking it out of the box"
I lost all stored data however. Now I store on the micro SD card.. So if I have to power wash I pop the card first.
Also since the card is removable I can pop it into the windows machine with a half TB drive) and store stuff.
My only complaint is that I can not easily print directly from the Chromebook but they are workign on that.