I think you might be carrying some Windows concepts over to the Linux world...
1. Windows and Linux processes don't work the same way. A Linux machine, or any Unix machine actually, will run many more processes at one time than a Windows machine; that is just how it is designed. You don't really need to pick through them and disable anything unless it is something obviously unnecessary (for example, a mail server daemon on a desktop). Kubuntu doesn't include anything like that on the normal install, so there is really nothing to worry about.
2. That sounds like it might be a driver issue, do you know what your sound hardware is?
3. There is no serious threat of spyware or viruses on a Linux machine, so there is nothing you need to do about it. There are AV programs for Linux, but they are designed to scan files which are being shared/traded between Windows machines over a Linux server. Make sure the system is kept updated, and use a strong password; that is basically it.