If I'm billing hourly and I'm billing an 8 hour day, I'm including a 30 minute lunch, regardless of rate. Anything longer than that is off the clock. If I'm billing 4 hours, then sure, no lunch. This is only true if I have a single client project on the go; if I'm billing piecemeal through the day (which I never want to do) then yes I'm eating on my own time.
I get being hesitant to bill for certain kinds of troubleshooting, but I think it comes down a lot to what the scope of the project is. If I'm on something that is multiple weeks of work, and I'm dealing with a problem that I would be encountering and would be expected to solve if I were working full-time, then it's billable.
> If I'm billing hourly and I'm billing an 8 hour day, I'm including a 30 minute lunch, regardless of rate.
If you bill daily or weekly, then great. If you bill hourly, then the only way this is okay is if you put "30 minutes lunch" on your bill and show that you're charging for it. There's a reason why it's very very hard to bill for 8 hours of work in a day, and that's because you don't work for 8 hours.
I get being hesitant to bill for certain kinds of troubleshooting, but I think it comes down a lot to what the scope of the project is. If I'm on something that is multiple weeks of work, and I'm dealing with a problem that I would be encountering and would be expected to solve if I were working full-time, then it's billable.