Originally Posted by: shapertakhim confused regarding chord progressions and on how to make one!!![/quote]
First let's distinguish between two things:

1. a chord progression
2. a series of chords played one after another

Originally Posted by: shapertakh
1. Do we actually need to STRICTLY follow such formulae or is it ok to strum out any sequence of chords? (i.e chords avaliable for a particular key and scale)[/quote]
Yes of course you can play whatever chords you want in any order. But it depends upon what you want to achieve. More on that below.
[QUOTE=shapertakh]
2. If these formulae do hold true, do we simply plug in the respective chords in the exact sequence or is there any other SCIENCE associated to it?

The science you are after with this question is called Functional Harmony
[QUOTE=shapertakh]
3. Can we imply multiple formulae for a single progression??? (if true then again whats to be done about the sequence and order of chords :confused: )

Start by asking "Why do we bother to change chords at all in a song? Why not simply use one chord all the way through?" It's possible to do, after all - and some songs, pieces of music actually do this. The main reason to change chords and use more than one in a song is to provide variety and thereby make the music sounds as if it going somewhere - hopeful somewhere purposeful.

In order to understand how changing chords can suggest motion in music we need an overview of Functional Harmony.

Building a chord on each note of the major scale results in the standard series of major and minor chords that are identified by Roman numerals:

I - ii - iii - IV - V - vi - vii dim - I

Each of these chords has a specific function as follows:

Tonic - I
Intermediate - iii, VI (can also serve as substitute for I in deceptive cadence)
Sub-dominant - ii, IV
Dominant - V, vii diminished

Baroque, Classical, Romantic & Modern music - all follow this basic outline of Functional Harmony regarding chord progressions:

Tonic, then Intermediate, then Sub-dominant, then Dominant, return to Tonic.

This can be reduced to:
Tonic, Dominant, Tonic
Dominant, Tonic
Tonic, Intermediate, Dominant, Tonic
Tonic, Sub-dominant, Dominant, Tonic

Notice the primary goal is always the proper cadence: Dominant, Tonic.

It is also possible to prolong the progression, for example:

Tonic, Intermediate, Tonic, Sub-dominant, Intermediate, Dominant, Tonic.

Notice the goal remains the same. It is of course possible to avoid using the Dominant - Tonic resolution in a song (or part of a song). This is a useful effect in it's own right. It can make the music sound more open-ended, or ongoing. Or even restless or wandering, due to not having a proper resolution as a "resting point" or end goal.

From there you need to understand the concept of applied dominant. If you are in C major, you can construct a chord progression such as:

I, iii, ii, V, I
(being: C maj, E min, D min, G7, C maj)

In order to "fill out" the piece, make it more beautiful, richly complex & "prepare for the arrival" of the E min from the C maj you can do this:

I, ii of iii, V of iii, iii...& so forth
(being: C maj, F# min, B7, E min...)

So you have deviated from pure C major, and are temporarily in the key of E minor but only long enough to prepare for its arrival, then you return to key of C major.

Notice the concept remains the same, though. The reason we use different chords is to provide variety & interest. And the reason we play certain chords in certain orders is to provide (or avoid) a sense of goal directed motion in the music.

Hope this helps.