I believe that "Facebook for HTC Sense" is just an interface, not a full-blown application like "Facebook" is. The interface version is what allows you to upload pics, syncs contacts, pushes FB contact pics to "People" and so on. Do "Remove account" on the plain "Facebook" entry and you can still upload pics, sync contacts, and so on.
As for FB contacts showing up in the dialer and SMS, first, under Menu, Settings, Accounts & sync, Facebook for HTC Sense, you can un-check "Sync Contacts". That's how I have mine set. That solves the dialer and SMS issue. Only people in *my* (Google) contact list appear. No FB friends do.
One other place, under "People", hit Menu, View, and only select what you want there. I have "Only contacts with phone number", "Google", and "Show auto Gmail contacts".