I will always try my best to help!
As for absolute particle placement, the majority of your placement is going to be in your emission section. You can always try for a base using face emission, even distrib, and a particle/face > 0 (Jittered), causing an equal amount on each face. Then you can use children to fill in the gaps with a random size to offer a nice variation. You can also use density vertex groups to offer something similar if you are dealing with a lot of geometry. Aside from that I do not think there is a really good way to obtain self-collision from particles (at least that's what I've already read). I believe that's where you have to step into soft body instead, and that might not be worth the time.
Actually, you could get a nice clump if you used the emitter instead, turned the gravity off, and had it emit your objects. Fine tune the size, set the start at 1, and end at 2 or 3, and step into the 2nd and 3rd frame. It will not work the very first time, but as soon as you step into that 2nd frame it will be very obvious what you need to change to close it up. This way you have a very nice even distribution, and a variance of size.
Well, I hope something in there helped!