Well splunkweb is actually a python based web server called cherrypy so in your list of processes you should have a splunkd plus something like python -O /opt/splunk etc etc.
Also its worth noting that it uses its own instance of Python, you don't need another independant install.
In your case, if you've done a ./splunk start and the ./splunk status command shows everything running, you probably just need to add a firewall rule for port 8000 on the CentOS box. On a new install by default it should probably be blocking it.
