Thanks alot for such a detailed info, your every post is sort of teaching stuff 
Secondly, I have very little knowledge about sound systems of cars, so I asked my friend for guidance regarding better sound system in limited budget. My friend told me that you can get a chinese system with LED that cost around 8-10K. It will be easy to operate but it has draw backs of average audio video quality plus it will be fixed. So, I prefered to buy a japanese jugari version.. even if it fails apna time nikal jai ga
And it also connect calls, but meri awaz nh ja rhi thii tu zaida mene bhi cher charh nh kii.
Thanks for the advice of cleaning 