I'd recommend not going for 40 hrs/week as this may conflict with the fact the you are/were a full-time student. This has been discussed before in this thread. I don't think there is an exact answer, but my guess is 25-30 hrs/week may be more reasonable. That said, I think there were cases were even 40 hrs/week was accepted. RA experience (or any work while studying) is no longer accepted in the CEC. For the PhD stream, it is still acceptable. It does not make your application weak. Some of us actually applied with only RA experience. Just make sure you check this thread for good reference letter templates.