Car Modellng Help

[will h]

Hi guys,wondered if you could answer a couple of questions about car modelling which is stopping me from progressing.Im using 3ds Max

1-When i want to create something which looks like an indentation in the bodywork,how do i do this.By indentation i mean,the car being made of different parts has to connect to one another and this creates a seem between the two (i.e) the doors or where the bonnet meets the front bumper.Just wondering how everyone models theres.I have tried different techniques,One of them was an extrusion inwards and another was detatching the selected area.Some Wire frame images to see poly placement would be really handy

2-final question,how do u model windows,do you make the bodywork first or do you model the window as your going?again some wire frames would be welcome

thanks in advance