Hello,
First of all: I would check your hosting account for malware - maybe you have been hacked (this is pretty common situation). I'm a web-security specialist and server admin, so I may efficiently check this.
These processes, per se, aren't dangerous - in the usual server configuration, the server "creates" single php process (/usr/bin/php) when a visitor opens the webpage. But, in fact, these processes shouldn't be live for a long time and/or shouldn't utilise too many resources.
Hard to guess - I'd like to take a look at this, analyse the configuration, check server logs etc. I may also make a copy of your website on another server (it may be one of my VPSes) and switch to this server for testing purposes (without any downtimes and with the ability to switch back immediately in any time).
Looking forward to hearing from you (send me a message even when I'm offline - most likely I'm hanging around),
Adam