1) AI Should check the bags through without any issues, although she might have to identify them and recheck them through the transfer desk in Delhi (I'm not sure about this. Its been a couple of years since I've done an International-International transfer at DEL)

2) I've had no problems with AI issuing BP for onward travel at LHR. They've done this for me even when the connection was on a separate PNR. Even if they don't it should be no problem to get a new one from the transfer desk

3) Yes http://www.newdelhiairport.in/eaton-smart.aspx Eaton Smart has an international airside option and it is probably what I'd do in this situation. They will send someone to meet her at the gate and guide her through transfer security and to the hotel. I've only stayed in the domestic wing which is in the Terminal but not airside so no access to shopping/restaurants etc (although they had mediocre restaurant/room service available). I think the International branch is past security though so it shouldn't be an issue. The Hotel is OK, perfectly clean etc but nothing special. I think I paid about 8500 INR for 8 hours

If she has an Indian Visa she might want to think about one of the airport hotel options. I normally stay at the Radisson Blu which is about 5-10 mins drive from arrivals/departures. They are building a load of new hotels which are even closer but I'm not sure if any of them are finished yet. Does increase the hassle factor though.

ETA: Oh I forgot, there are also some sleep pods airside http://www.newdelhiairport.in/sleepi...s-airport.aspx, Never tried one though