svchost is a host process for various windows processes. There can be many of them running at the same time, as new processes will start a new copy of svchost instead of jamming the existing one. Check
this microsoft info for more. I suggest not to try to disable it.
A good and safe way to cut down processes is to look at the Preferences section of programs running in TaskBar or TaskManager, trying to find and disable "start when Windows starts" and the likes. When you're at it, you'd also might want to disable their automatic updating.
And once again, if you just don't know, Google is your friend. It tells that
plugin-container is a component belonging to Mozilla Firefox and
s4tsr.exe is most likely a legit program for disabling
EHCI. As you can see, there's many kind of opinions of any process, including virus warnings. Knowing the brands and makers of your computer components may help you determine, whether there's a virus in disguise or not. Also look for any kind of typos, as viruses may use familiar looking names. For the computer a familiar looking name is a totally different animal than the real thing, and so is a correctly named thingy in a wrong place. Thus a running svchost.exe situating in Windows/system32 sounds like the real thing, but if it were in the Program Files folder, or named as svch0st.exe, it most likely would be a virus.
