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.

तुम पास आये, यूँ मुस्कुराये यूँ ... कुछ कुछ होता है

An interesting description of being in a state of love.
"...बेचैनियों में चैन, न जाने क्यों, आने लगा..."
The singer sings "I don't know why I find peace even when I am consumed by lack of peace." Anyone who has experienced romantic love can probably relate to this seemingly anomalous statement.

एक दिन आप यूं हमको मिल जायेंगे

The imagination that the lovers have on how they have fallen in love is a beautiful expression. Although real life love may not always be able to be expressed in such glorious terms, it is useful to see such possibilities.

It seems like there is no match for Javed Akhtar, the lyricist.

साजन, तुमसे, प्यार की लड़ाई में

A pair different from the lead actor and actress dances for this song, but the lines convey the feelings that the lead pair is going through. This is probably a rare occurrence in Bollywood music.

कांची रे, कांची रे, प्रीत मेरी साँची

Lovers argue why each should not leave the other ... The true meaning cannot be conveyed by a drab translation ... you have to experience the song in all its melody and semantics. I didn't discover until recently that the raag ♫भूपाली is behind this melody.

गाडी बुला रही है, सीटी बजा रही है

It is one of the unique characteristics of Bollywood lyricists to derive pragmatic values of life by observing everyday things — in this case a train. For example:

"responsibility of carrying people around, fire in its heart, smoke on its lips ... still keeps on singing, i.e., moving"
"[the train] won't bother about all that [thunder, rain & lightning], moves at the drop of signal, day or night"

Add to it the melodic singing Kishore Kumar can provide. A treat, although a nostalgic one.

ये ज़िन्दगी उसीकी है, जो किसी का हो गया

"The world is that person's, who belongs to someone else, gets 'lost' in love." In other words, if you are not loved for any reason, it can be very lonely and can give rise to all sorts of desperation.

Ultimately, while union with a lover and, by implication, with God is what is desired by everyone, it takes a skillful poet to bring that about in words, and a beautiful voice like what Lata Mangeshkar and Shreya Ghoshal have, to impart melody.

ज़रा सी दिल में दे जगा तू

When you understand the variety of pleadings of the male with the female for her love, you wonder how spontaneous this feelings can be in real people. But, you have to appreciate the poet's attempt to capture these thoughts.

The manner in which the singing is punctuated by the screeching halt of the automobile, and the dialogue about betting in a game of cricket,

"When you are so good at betting, why don't you become a bookie yourself?",

you have to credit the Bollywood creativity!

किसका चेहरा अब मैं देखूँ

An interesting way to express how each lover has come to choose the other.

नीला आसमाँ सो गया (male)

It is rather rare that an actor or an actress also provides the singing based on a classical raag. Amitabh Bachchan does this well here. A musical pun, in a female voice later in the story, recounts the heartbreak.

Right Here Waiting

I had heard this song some years ago, and was pleasantly surprised to find it on YouTube.

This song describes the sentiment when lovers [have to] drift apart. The instrumental melody itself is very hummable. This song must have been so popular that it has garnered a Wikipedia article.

दो लफ़्ज़ों की है, दिल की कहानी

"The tale of [two] hearts, is made of [only] two words ... love or youth."

If you interpret love or youth to mean true love or infatuation, you can see some justification in this simplified interpretation. It is said that Asha Bhonsle herself regards this song as one of her best renditions.

छूकर मेरे मन को, किया तूने क्या इशारा

"By touching my heart [or mind], what a gesture have you made?
This season changed, and the entire world seems lovely, wonderful."

Considering that an immensely desirable quality in a human being is to touch another at an emotional or at an intellectual level, it is only appropriate to have this quality immortalized in a song, crafted to hummable melody that only a Kishore Kumar can create.

अल्लाह तेरो नाम, ईश्वर तेरो नाम

This song brings out the secular nature of God, although only two forms of God are mentioned here:

1. Allah of the Muslim faith, 
2. Eswar of the Hindu faith. 

It also wishes for goodness in the world, in expressing that:

1. Everyone be blessed with good mind
2. Wives not lose their husbands. (This is probably a reflection of the time; women tended to be more dependent on men those days than nowadays).
3. Mothers' and sisters' not fulfilling their hopes
4. Life not be stifled by a [weak] body
5. Everyone be blessed with knowledge of God

The foregoing is nothing but an elaboration of another well-known Sanskrit phrase, वसुदैव कुटुम्बकं, or "The whole world is one family".

Above all, it is a beautiful rendering by the incomparable Lata Mangeshkar.