In simple words, system processes are processes owned by the Linux OS itself to perform internal OS activities. For example, "init"
Application processes - this is what you as a Linux user execute applications. Example, when you run Apache, you will see httpd process.
What command to check this ?
#ps auxw
or
# top
No idea what process is this, but you can verify it checking what binary triggers this. Then go lookup it using your package manager the path of this binary to tell you what is the binary that created this process is actually function as.
dsp - reminds me of sound related process. I might be wrong.
