Adding a return vent to a hot office

I have an office with a significant amount of computer equipment in it that generates quite a bit of heat and is regularly 3-12 degrees warmer than the rest of the house when I'm working in there with the doors closed. (My house is a pretty large 5-bedroom house, so I'm not too worried about this affecting any large-scale balance.) Unfortunately, this room has no air intake vent. It does have a register from the HVAC. The room regulates its temperature fairly well with the doors open and I can feel a draft blowing out through the cracks in the doors when they're closed, so I think an air return is needed.

It's a squarish room with the HVAC register (4" x 10") under the window on the floor and the doors are on the opposite side of the room next to an air retrun vent in the hallway (it's quite close to the furnace and seems like a rather large cavity, not a long run so minimal friction). I've added a (bad) drawing of my office and what's on the outside walls. There is a basement below and a bedroom above this office, so neither the ceiling nor floor are really accessible.

Office Layout (the office is surrounded by black lines, the grey lines just show the outside rooms/areas, red show existing HVAC things):

Other than right around the door area, most of the walls are fairly off-limits due to what's on the other side (obviously not punching a hole into the garage, the bathroom is already too small, not making it smaller, and don't want to add anything to the foyer area for aesthetic reasons). I think the two areas that provide the most opportunity for adding an air return vent are either tapping directly into the air return cavity (shared with the hallway) or just opening up a new return pseudo-duct over the doors from the office to the hallway.

My concerns (I'm an engineer but no HVAC guy):

1. Because I largely want to remove heat year-round, I think the return vent should be on the wall near the ceiling (this is fortunate if I go over the door into the hall).
2. I'm concerned about noise transfer from the hall to the office or office to hall (I have a 3yr old, nuff said)
3. I'm not sure what HVAC codes & permits might be needed in this area of Indiana (Carmel). I think I might need a permit of some sort if I do HVAC duct work.
4. Something in my gut tells me I shouldn't tap into that air return cavity directly with the hallway having a large vent right there at the same spot on the other side of the cavity.
5. I understand this might not be 100% perfect with the heat generation in the office, but I'd like a large improvement and I think this will do it. Adding additional air conditioning into this room is likely too costly of a solution.

My questions:

1. Is there an obvious answer here? Is it bad to just vent the hot air into the hallway next to that air return vent out there?
2. If I go above the door, should I punch one hole in my office as high as possible with the second hole in the hallway as low as possible to maximize hot air going out while minimizing noise transfer?
3. How large should the holes be? If I go above the doors, should just 1 work or should I put 2 in, one over each door?
4. Should I use a "register booster" or other powered device to help push air through the return vent that I'm adding?
5. If I cut a hole into the existing cavity, how do I keep all of that drywall dust from going into my furnace (filter)? Or do I just do that and swap the filter out when I'm all done?
6. Is there something else I should be asking? I can definitely cut some holes into drywall but this is all new to me.