Hi Ellie
There are lots of posts on here asking for help with things like this for college assignments. Firstly, your college should have explained to you what contra indications are and supplied you with some course notes. If they haven't, I would ask your tutor. Secondly, I would recommend getting a good technicians book. Encyclopedia of Nails is an excellent start and if you can't afford to buy one you will certainly be able to borrow one from a main library. I got all of my contra indication information out of this book and comes in handy all the time.
With regard to the difference between beauty therapist and senior beauty therapist, all I can suggest is having a think about it a little more. What additional duties, skills and qualities do you think a senior therapist should have?
Sometimes the questions aren't as tricky as they sound. hth x