- No. (BTW bugs are not intentional features.) Only when using a beta version should you expect major problems.
What you really should be looking for is whether or not your hardware works with Ubuntu. Check that upfront by looking online or by using the Live feature of the installer. Most hardware is fine with Linux, however, and the main problem is generally graphics. AMD and NVIDIA are usually fine (although NVIDIA does cause problems). Other graphics cards are a hit or miss. SIS (if those are still around) is crap.
Another thing to worry about is what WiFi card you have. If you have one and it's Broadcom, take a look here. You need to be somewhat comfortable with a command line to follow it.
Printers: HP is good. Most others are problematic if they're newer models (In general Linux works better on hardware that was released a while ago since some volunteer needs to add it to the hardware stack and it can take some time before someone with the necessary knowledge can get a hold of the hardware).
- No. Security on Linux in general is as good as it gets, and it ismuch better than how Microsoft does it. But with security it is most of the time the user that is the problem: clicking on stuff one should not click; installing stuff you should not install; etc. Our software center is wonderful in that regard: no browsing the web for software, having you end up on some obscure website. Not handing out your admin password helps a lot.
The best thing to do is to install the newest LTS version (now 14.04). That one tends to be rock solid after a few months of release and only offers the next LTS version as an upgrade path by default.
And just to make it clear: my 70 year old mother is using Ubuntu 14.04 for internet, emails, newsletters, listening to music, and watching YouTube videos. She even told me she found a very good Dutch instruction site for using Libreoffice Writer. And she brags to her friends about having a system that does not get viruses when one of them complains about Windows needing to be re-installed.
If she can use it so can you.