Likert item data- which test to use to see if there is a relationship between groups

I have been given some data and I am trying to statistically analysis it. The data is from a survey in which 202 students were asked what is important when considering a university.
They were given 15 things (sets) such as cost, course options, location ext and asked to rate it using a scale of not important, not that important, not sure, important and very important.

I have assigned this rating numbers from not important: 1 to very important: 5.
I am trying to test for two things
1) if there are any relationships between all the different sets of data,
2) if there is a correlation between students rating of one thing and their rating for another, e.g. is the importance a student gives to cost correlated to the important they give to location.

I thought that I could do this by using the chi squared test of independence but I am unsure if I can/ how to use it to compare 15 sets with 202 students ranking each set. I have been searching on line and I found a test called Friedman two-way analysis of variance which I think I may be able to use, although I am not sure and I cannot find a good explanation of it.
For the second question I think that I might be able to use Pearson's correlation test, is this correct?

If I have been unclear in explaining my problem please ask me questions. Any advise and help would be much appreciated.

I have posted this in this section as I think it is the correct one but if you think another one is more suitable please let me know.

Thank you.