Doubts about some expressions

[dilodi83]

Today I was watching an English movie and I wrote down three sentences I have some doubts about. I hope you can help me with these three.

1) A: Don't forget to get the present for Alice's birthday party.
B: Don't worry, I'll go and get it at 5 o' clock.
A: And remember to stay in touch with Paul. He has to give a lift to Joanna too.
B: Sure, I will.
C, (who is Alice) : Hey girls! what are you up to?
A: Oh, nothing important...how are you today? Happy birthday!

Now, what's the meaning of the sentence in bold and when are we supposed to use it?
May it mean "What are you doing?", if it may, what's the difference between the two?

2) Is there a difference between "to keep one's mind off problems" and "to take one's mind off problems" or are "keep" and "take" the same?

3) Is there any difference between "to put something aside" and "to set something aside"?
Ex. I think you should put/set your emotions aside.
Why don't you set/put your money aside?

[5jj]

You should know by now that we ask people to start separate threads for completely unrelated questions. I'll look at the first of yours.

'What are you up to?' does indeed mean 'what are you doing?' It may imply that the person asking the question thinks that the other people are doing something suspicious, but that will depend on the context and the tone of voice in which the question is asked

[SoothingDave]

If you have problems on your mind, you would first need to take your mind off of your problems, then you could keep your mind off of your problems.