What are best practices for using Yoghurt as a Marinade? I'm cooking for 30, Lamb Chops are on the menu and I want to do them in a Yogurt Marinade. I've done Yogurt Marinades with mixed results and I wonder if there are some best practices? specifically:


How long should I marinade? With vinegar based marinades you don't want to marinate for longer than 2 hours. Is this also true with Yoghurt Marinades? If not, what is the idea amount of time to Marinate.
I heard somewhere that you shouldn't add salt when Marinading with Yohurt until after the meat is Marinated. Is this true and if so why?
lemon is an important flavour to this kind of dish. Can I add lemon to the yoghurt, or will that make it curdle or do something else negative to the dish?
Is there anything else important to consider when using Yogurt as a Marinade?


If additionally you could break it down in terms of chemical processes, that would be sweet. I'm a bit of a food science nerd.
thank you very much
To answer part 1. I recently watched the Chicken Tikka Masala episode from Blumethals "Further Adventures in Search of Perfection". The recipe calls for  marinading the chicken for quite a long time. A transcribed recipe says 10 hours: http://www.dominicsayers.com/documents/ChickenTikkaMasala.pdf.

They also go on to compare the results of a yogurt marinade and a yogurt-less marinade on chicken under an MRI scanner. I don't know if this is valid, but the yogurt apparently had an effect.