The first equation is normalized so that it can be obtained in one of the general forms for which inverse is known. So it is easier to convert to time domain.
The second equation is just mutliplying by complex conjugate to make the denminator a real part
the thing u have done in the first case is not normalisation at all...
just u have to converted to standard form to get the result...
as it is known tat ....
1/(s+a) ------------->>>> e(-at)
in ur second question ...multiplication by conjugation is done to separate out real and imaginary parts...
we need real and imaginary parts separately in most of the cases....
like in signals and systems...in the use of phasors...real part corresponds to the output of cos(wt) and imaginary part to sin(wt)...