Ok, thanks for your time in writing a detailed explanation, BUT little bit of confusion still left. I have the following string :

$GPRMC,123339.000,A,5134.2770,N,00007.8480,E,1.14, 254.38,271009,,*09

Can you please show me as to how to convert "5134.2770" & "00007.8480" into degrees - minutes - seconds in PBP + speed to Km/H.
I have done this online and the answer is
Degrees, Minutes & Seconds
Latitude - Longitude
N51 34 16 - W0 07 50 and 2.111 Km/Hr (Though it should be 0 Km/Hr as Module is stationary)

Also what is checksum? and what it is used for?

Your effort will be much appreciated. Many Thanks