न जाने क्या हो गया है तुम्हे देखकर

Lilting tunes are a specialty of this song while it expresses feelings of romantic love.

All izz well

Considerable poetic skill is required to craft a song using multiple languages. (It can also be argued that it is easier find rhythmic words if you use multiple languages). This song is a good composition that tries to provide a simple, lighthearted and humorous outlook on life.

आये हो मेरी ज़िंदगी में, तुम बहार बनके

"You have come into my life like the spring ..." Singing provides an effect that mere prose cannot convey.

होशवालों को ख़बर क्या बेहूदी क्या चीज़ है

TBA

Sources:

... हैं गुज़ारिश ...

[Note. Notation for humming needs to be added.]
You have to see the movie to appreciate the context for the song, but suffice it to say that the lyricist, Prasoon Joshi, has deftly described the tumult in a man's heart as he awaits a 'yes' from his lover.
The meanings presented here are based on those provided by another blogger, The Bollywood Fan. (Netizens are welcome to comment on the meanings and, in fact, on the lyrics too). There are several music videos on YouTube, and one is here.
Another rendering by Soumen Nandi of Sa Re Ga Ma Pa 2009.
Google Hindi-to-English Translator translates गुज़ारिश as 'request'.