I'm an undergraduate and currently applying to summer research programs that ask for letters of recommendation. Last summer, I did research at a university with a professor who I'm planning on asking for a letter. He mentioned how he would like more people who are studying computer science to apply to his summer program, so I was thinking of telling him after the request for the letter that as a token of my appreciation, I would be happy to encourage people in the computer science department to apply to the program.
Another professor who I was considering asking is thinking of teaching a course in the fall that I want to take. I was also thinking of asking him following the request for the letter of recommendation about whether he is still planning to teach the course and that I would like to take that course with him in the fall.
My intention is to give something to get something even if both professors would most likely write me a letter regardless of whether or not I "offered" them something in return. Are these things that most professors would appreciate, or do they sound too business-like and Machiavellian (in that they are part of an email asking for a letter of recommendation)? Should I just straight up ask for the letters?