I haven't touch statistics for year and now I came back to find I am totally lost.
Here is one of the question that I wish to know how to solve it, in terms of steps, so that I can gain back memory about it.

I know it is a bit too much, but I am really very very lost and depressed, help.

These types of questions are straightforward, you just have to look up the appropriate technique (and get familiar with the terminology). According to
http://www.fmi.uni-sofia.bg/vesta/Virtual_Labs/interval/interval6.html [Broken] :
let S^2 be the sample variance of normally distributed data
let [tex]\chi^2_{n,a}[/tex] be the number x such that if X has a [tex]\chi^2[/tex] distribution with n degrees of freedom , then P(X < x) = a.
then
[tex]\left(\frac{n-1}{\chi^2_{n-1,1-a/2}}S^2,\frac{n-1}{\chi^2_{n-1,a/2}}S^2\right)[/tex]
is a 1-a confidence interval for the distribution variance. You can calculate this interval numerically using a table for the [tex]\chi^2[/tex] distribution or some stats software.