General question about building a Custom Rom

Hi all

Was wondering if someone could point me towards the best way forward with a couple of requirements for a project. This is for a Use Your Phone Less campaign and so we would like to give away phones with a completely modified ROM, as part of a larger promotion. I am a developer but have never dabbled with Android.

The requirements are:

1. Modified ROM, as in it is completely stripped down. Completely (more than a Feature Phone). There is only the ability to make calls, send and receive sms and take pics. That's it.
2. We want to modify the functionality of the those three things so that if a call/sms/photo is made, a simple dialog box appears with a message.

That's it.
1. Now for the first requirement, it appears that one can modify either a Stock Deodex ROM or an already customised rom such as Cyanogen and deleted apks from the System image, and then recompile it and flash all the phones with this ROM. Is this the simplest method? And does it indeed strip everything out?

2. For the second requirement, can this be done by extracting the apks, modifying the java and recompiling? Or can this only be done by downloading the Android source, modifying and then recompiling? This appears to be a monstrous task from what I've read.

And are there any simple apps that will allow me to do any of the above? The simpler the better!

If this isn't the right forum, then it would be great if you could give me a pointer to where.

Thanks!

Drew