Are there some good online tutorials to learn more advanced Excel?

Youtube is the best source for it, but Microsfot itself provides some very resources, check;

http://office.microsoft.com/en-us/excel-help/training-courses-for-excel-2013-HA.aspx

Another very good resource;

http://www.gcflearnfree.org/excel

And on Facebook you can check, lot of very good pages there, ll update u on daily basis.

You can also see  http://www.excel-pratique.com/en/index.php

very good site

Yes, but the best way is think about the problem and try to resolve it yourself first and even you can ask from one who already have done that.