CFD Online Discussion Forums - setting up a simulation with multiple interactions

I am a complete newbie to openFOAM & CFD, so best regards to my alien jargon.

I want to set up a simulation that has more than 2 moving sets. A cursory web search came up with this link, explaining that interFoam can do two incompressible fluids (including moving meshes).

Specifically, I aim to set up a simulation that has (1) a large set of identical incompressible meshes (think a bucket full of screws, only modeled as cubes), covered in (2) a viscous fluid, on (3) a moving porous platform, interacting with (4) an incompressible gas at a velocity from an inlet to an outlet.

My current plan is to break this up into separate parts to make sure that I am getting the parts done right. I appreciate help getting along this path and putting them together, because I have a lot of questions, but I appreciate help asking the right ones as well.

First, I am going to try to simulate 1 and 2 in its simplest state, with 1 in a mesh volume, covered in alpha1 (2), to set up having a mesh covered in another volume.

Second, I wish to simulate the interactions of 3 moving inside 4.

Third, I would like to bring them together for the simulation of the whole.

Please, help me to correct false assumptions and understand the best way of modeling this.

For the first simulation, I assumed that interFoam would be the solver of choice after watching this video. Ideally, I would take a *.step file that has the solid volume and another *.step file with the fluid modeled around it, and place them in a larger volume. I would use Salome, for example, to make both meshes separately (although together is fine as well), and export that to unv file(s), and use ideasUnvToFoam to bring them in. Would this work? If so, how would I define the one mesh volume to be my viscous fluid? If not, what would work?

For my second simulation, I really need help. I can't find anything (perhaps because I don't know what to look for) that will let me define one (rigid) mesh as moving through the other (perhaps with symmetry planes at the interaction instead of walls). Since this particular simulation has a moving mesh and moving air, I also assumed interFoam is the solver of choice, but I'm not sure if icoFoam is applicable to this case.

To bring them together in the third simulation (where I have an array of 1 covered in 2, moving on 3, interacting with 4), is interFoam capable of this? Otherwise, is there a separate solver, like multiphaseInterFoam that would be more appropriate?

I have used SALOME successfully once for generating meshes from a standard step file and using that in a simulation. If possible, I would prefer to not have to learn yet another tool, but if it would make my life easier (and is FOSS), I would be more than willing. Any and all help here is much appreciated.