I'm sorry that you are feeling victimised/isolated by others in your workplace. I'm in a senior management position and have a masters in business management and have seen cases like yours before often they turn out okay. I disagree that this is the start of a termination, although your behaviour from this point onward may trigger it.
I would caution against just clocking in and out, if I were your boss I would be watching your interaction with your team members with great interest from this point forward.
I would encourage you to honestly examine your interaction with others in the workplace to date. There is something that is upsetting more then just one individual, have you analysed the organisational dynamics of your team to ensure that your behaviour at work is appropriate for this dynamic?
I'm also curious as to the reasons for your colleagues being so overwhelmed by work that your boss has directed you to take on a few of their tasks when you have time to do low level jobs such as filling envelopes. If I were to have directed a subordinate as you have been it would probably be because I realised that there were interpersonal issues and was attempting to get you to repair them or because I didn't feel as though you were carrying enough of the workload.
The asking questions problem is difficult to analyse too. Could it be that your boss/colleagues think you are questioning them? Whilst I encourage questions in my work place I get very annoyed if the poser is wasting my, or one of my team leaders, time by asking questions that they could source the answers for themselves, I tend to judge that person as being lazy and lacking initiative. If it's a case of the same question being asked consistently perhaps you could start a small personal reference journal where you record the answers for when you need them next? I always do this when I'm learning a new system or process, it's a really good tool!
I'm sorry that this sounds harsh, I'm just trying to think of how I would counsel this situation in my workplace and am trying to identify possible friction points between you and your boss so you can avoid them..
Sorry for typos on my phone!