Hi
I'm quite new to xpe too but I'm working with the tools since 2007 so now I
can give you some suggestion based on the steps I did from the totally
unknowing to a working image.
1) It depends seriously from the components you puts and how the image is
big: there's a tutorial in the help of xpe that explain many ways for
decrease image footprint and optimize boot times. personally I started from a
boot time of 55 seconds and now the system boot in 25 seconds, using the
advices in the help. you can navigate also xpe forums finding tips about
disabling features like PnP and other...
2)Ewf is quite easy to use: just put components that add the ewf feature to
your run-time image and, another time, read the help; it is important to know
difference from ewf and fbwf and if you are planning to use them integrated
in the application or not ( API).
3)Easy: just remember to find out the app requirement in respect to sytem
and components. there's a lot of way to find the components needed to run
your app.
4)You have to find the component related to CMD.exe that is windows command
processor, but please don't forget to put in the image the possibility to
enter it maybe using the run command (in the user interface core!)

an advice that I can give you is using a design template, because it solves
a lot of problem in future develpment and debugging!

I'm developing an image similar to what you are doing now, so if you want I
can help with suggestion, but please remember that I'm not a "GURU", so, for
particular problems, ask the forum!

Good luck!

Anakin