Are these good languages to learn?

Next year I'm going to be doing an arts course and I was thinking of doing a major in two different languages- Chinese(mandarin) and Arabic.

Is this a good idea? I remember reading somewhere that learning arabic is pointless because the dialects between countries varies so much that even learning the standard language tends to be useless. Is this true?

Also, would having knowledge of japanese help in learning chinese? I learnt Japanese throughout primary and highschool and was wondering if having knowledge of kanji could aid in learning chinese at all.

The university I plan on going to also offers Indonesian and Italian. Would either of those be worth learning at all?

>>6
But nobody speaks standard arabic in real life, while the majority of chinese has standard chinese(mandarin) as their mother tongue