2. DSM struts used on the CSM, does it work? Too long? Too stiff? If it works, do you still need to slot the strut holes or do they align?
Yes, the front awd dsm struts work great with awd dsm lowering springs (gives a 2" drop depending on springs used, stock awd springs will gain about 2" height and look silly), fwd struts might be too long. You have to swap the csm upper strut plate onto the dsm strut, then it bolts up exactly the same.
4. If you don't slot the struts, the wheels will leaning in or out?
Slot them using what, awd dsm struts? Don't need to. Changing hubs on the other hand, VR4 hubs/knuckles will give you 3* of positive camber, not sure about expo stuff. It's safer/easier to do camber plates IMO.
5. Is there a combination of (2g front and rear spring/spring hats) or (1g rear springs/spring hats) and strut plates with the CSM struts that would work? I don't like the idea of slotting struts.
http://www.4g61t.org/forum/viewtopic.php?f=10&t=26736
6. So, will the seal identified earlier in the thread to allow use of the CSM axle with the expo knuckle, work on the DSM knuckle?
There is a seal that can be used in dsm hubs/knuckles that will allow use of the turbo mirage axles, not sure which seal you're referencing though but it can be done, a lot of people like to swap over to 5 lug setups.