You should not be struggling with this. Go ahead and construct the confidence interval.
Find the Sample Mean.
Find the Sample Standard Deviation.
Find the Standard Deviation of the Sample Mean. <== This is the important part that will allow you to answer the second question.
Decide if you can use a z-score or a t-score.
Find the right value for a 90% confidence interval. Is it one-tail or two-tail?
That's a good start. Show us what you get and we can move on from there.