Is it difficult to learn Greek?

I've been reading a Teach Yourself series book where they explain a very easy way to learn Portuguese. I think it's extremely easy for me because I'm a native Spanish speaker so those are very similar. The thing is, I just had a look at the Greek version and it's madness!!! The guy who invented that language must had been crazy or had issues, I don't know!!!

Languages known:
Spanish
English

Learning: French

Going to learn:
Arabic
Chinese

After Arabic and Chinese, is it more rational to learn Greek, Japanese, or Portuguese? For example, for business purposes.

Latin-Roman people ( Spanish,Portuguese and Italians )are so different than Slavic people...
Nordic people( Norvegian,Swedish, German) are also so different than Greek people...
Etc,etc...
But they are all White people...Homo Sapiens people...

Why, how and when did they choose to do the things in different ways ? (languages,cultures,etc..)

i want to know what is the set meaning of nao me xinga

as i was saying i do speak greek and english can you help if you speak this languages to tell me what is this mean? it is portuguese does it means den me xegelas or something like this i would appreciate it thanks so much

Don't know if I'm asking this question right, but I mean do they assign things "maleness" or "femaleness" like in French, Spanish Portuguese, etc?

If so, what is the gender of pneuma, 'breath'?