Sanket,
I do not think video port(VPIF) is avilable in AM1705 for camera interface, Please refer the datasheet of AM1705
http://www.ti.com/lit/ds/sprs657d/sprs657d.pdf
For USB Interface of 3G, refer the below wiki article,
http://processors.wiki.ti.com/index.php/Android-USB-3G-Modem-Integration
http://processors.wiki.ti.com/index.php/TI-Android-ICS-PortingGuide#USB_3G_Modem
General Routing and Placement Guideline for USB Interface, refer this wiki article,
http://processors.wiki.ti.com/index.php/OMAPL1xx,_AM1xx,_C674x,_DA8xx_USB_Hardware_Design_Guide
In addition you can find some details through the TI.com documents and the TI Wiki Pages.
Be sure to search those for helpful information and to browse for the questions others may have asked on similar topics.