Feedback: Using Google for idioms and fixed expressions.
1. On behalf. According to a traditional rule, you should use in behalf of to mean "for the benefit of" and on behalf of to mean "on the part of". However, the two phrases are often used interchangeably.
2. It's as easy as 1,2,3 or A B C or pie, are probably the most frequent.
3. Grateful was probably the word you found, as it is closely attached to the construction I would be.