my system with a 120gb ssd boots in about 1min, i believe most of my bios settings are set to default..
you can use that type of board, but you need to check a couple things. so far all the boards like that i have read of use 19v power. as long as they use a voltage near that, they can be used in cars. you just require a power supply like the carnetix 1900, or 2140.
motherboard--for general use, the atom, or the more recent amd zacate lineup should be adequate. as i'm sure you've found, it's no i5, but it does it's duty...
i do not recommend any usb screens as a primary display. they will not display anything until after windows loads, so that means that any pre-windows errors will never be displayed. there is also the issue where they use processing power for video screen updates-- because the usb lines go through the processor, there is no way that a usb screen can take advantage of things like the ion chipset. and with the limited processing power of the atom/zacate, it could take too much processing power, and cause problems with stuttering audio.
personally, i have used 3 different screens(escalating in price and performance). when money is an issue, the extra options are a little frivolous. if you have the extra money for the project, then the options are nice to have. the biggest difference is if you own a convertible, and is the reason that i kept spending money on screens. if you have a hard top car, then i don't believe that you will need anything more then a high brightness screen.
so far, i have really enjoyed my lilliput 669 screen the most, because it has 3 input options over my first screen which only had a vga input.