Great post. having managed to get in my local bir kitchen 3 times now, i can offer the following advice.
1) find a bir where they are not too formal , and quite friendly, and relaxed.
2) spend lots of money over 6 months, and make some friends with the waiters.
3) let them know you are an amateur cook with a real interest in indian cooking.
4) after 6 months order a decent sized takeaway on a quiet day (e.g. mondays), and ask if you could see it being cooked.
5) if you get this far, make friends with the chef before expecting to have all your questions answered. At this stage resist asking too much, and ruining all your hard work! keep things friendly and hopefully you might get in again.
6) dont get too serious as they will think you are opening your own rival BIR restaurant. I nearly made this mistake!
7)Dont ask basic questions such as 'whats in the spice mix', as all that info is already well documented on this site. Ask questions about things we dont know e.g does madras have just vegetable oil in it, or does it use reclaimed oil? Or ask them if madras has lemon or lime juice in it? if so how much?
8)what we really need on this site, is definate, accurate, recipies for the main bir dishes. therefore, ask questions about what ingredients are included in e.g chicken bhuna, and what quantities of things, such as garlic, spice mix are used in this dish.
9) Observe what they do,and write it down as soon as you leave the restaurant. specifically, the ingedients in each dish, and the amounts, and cooking times.
If you find a friendly little restaurant, its quite easy to get a demo. and believe me its bloddy marvelous! the best day out i had all year! how sad, lol ;D