The last two issues likely have something to do with individual call rules. You'll want to log in as each user and look at the call rules there. Calls will follow the first set of rules that match both the status and the time frame conditions. Make sure any rule to "send to voicemail" only applies to Direct Calls and not All Calls or Queue Calls. Also note that a user's status is only as good as the call rules it triggers; the only built-in call rule sets are for "Available" and "Do Not Disturb". If users want to stop receiving queue calls, the best option is to make the queue log-in/log-out or use the queue Pause functionality from Switchboard; if you want to tie it to a certain status (Away or otherwise), make a set of call rules to trigger when you set that status and choose to Decline Queue Calls.
Any weirdness you're experiencing could be (and likely is) explained by the version you're running. They're up to Switchvox 8 now, and at the very least, you're several releases behind the latest version of 6. If there's any way for you to get up to date it would be recommended.
Is there something that makes you think the drives are bad? You may able to gather some information on them from the System Information page.