Learning new language not only can help you prevent certain diseases in old age, it also activates different parts of your brain when you speak it and you even start to think differently. I've read some research and scientists say that bilingual children are easier to educate.
Yes. Another study of foreign languages contributes to the development of concentration and interaction with other people. Those who know several languages communicate more easily with other people and have a good memory.
i speak french,spanish,german very well, i dont think i can learn any more languages.
If you really speak these languages very well as you say then you can definitely take on a new one and learn that too well enough. It gets more difficult after 30 but your brain is already well trained so you should be fine till 40, easily!