tips and meals for private guides

If they have provided the service for which you have contracted, yes to both questions.

You probably do need to tip your guides...you'll have to consider the proper amount based on their fees and how many people are in your group. I think you should probably tip the driver as well. As for buying meals in addition to tips, that seems like overkill to me. If tips weren't expected, then buying a meal would be a nice alternative. Of course, I'm sure Mike would appreciate a meal in addition to his fee and tip, and there's no harm in spending an extra few bucks for some grub if you like his service and you feel like doing both. If nothing else, you'll be a good ambassador for fellow tourists. I'm no expert...that's just my two cents.

I have only occasionally done guided tours in Europe, and have never tipped. Tipping is not the norm in Europe and Europeans do not tip like North Americans. It is not expected. Would I tip and would I buy their meals - no I would not but if it makes you feel more comfortable to do so, that is fine.

I agree with Bob. Yes to both. For me, it's the right thing to do. I would never hire someone to provide a service for me and not tip them. Low class imo.

Personally I think it depends. If you hire a private personal guide operating on their own why should you have to tip them when you're already paying them what they asked for. If, on the other hand, you're hiring a guide from a company that pays them a salary, then if you're thrilled with their performance you should tip them accordingly. Most Americans tip automatically regardless of service, it's what we do here (even though I don't agree with that mentality), we should be more discriminating about tipping. If you're hiring a guide for the whole day I don't see anything wrong with asking up front what is expected regarding their meals and make your decision based on that information.