Dominator Slots

Recently purchased a drag car and trying to tune so I can take to the strip for my first ever trip down the 1/4 mile

HOF155 – Dominator Spheres This pack contains three metal kits, each composed of a robotic body propelled by tentacles, and a sprue of six different limbs which can be added in any of the six mounting slots and bent to your choice of pose, meaning huge variety. Limbs are: Grabbing Claws, Circular Saw, Laser Cutter, and Energy Blaster. FPS Dominator Mode – To enter FPS Dominator mode, simply HOLD the top P1/LEFT SELECT/PADDLE button and press the top P2/RIGHT SELECT/ PADDLE button. You will know you have correctly entered FPS Dominator mode as identified by the Gearhead Eyes glowing LIME GREEN.

Dominator Slot Car Chassis

I have a 3-circuit L-9375, that has no intermediate air bleeds and the blocks have no power valve orifices. Just bolted the carb back on tonight after clean and rebuild. Before that though, the engine suffered from partial throttle stumble, the plugs were fouled and exhaust was pig rich (I have not used an O2 sensor to measure). I'm hoping the rebuild will help things.
Also, I can't see any of the T-slot from the bottom view with throttle plates closed. As I understand it, opinions vary on whether this is significant. I have read several threads about the 2 circuit conversion and wondering if I need to convert.
The car is a 72 Duster, 446, comp 650, 12:1, 3500 stall, 4:56 gears, and 3300lbs with driver. Its going to be mainly strip with light street use.
Questions:

Dominator Slot Car Chassis

1. I finding it tough to tune the idle. Only pulling about 6.5 ' vacuum and it doesn't seem to vary much when I adjust the idle screws (though I haven't tried yet since the cleanup).
2. What effect does not having intermediate bleeds have?
3. Should I to switch to 2 circuit?
4. Should I elongate the T-slots to provide the .010'-.020' past the throttle plates that some suggest?
Thanks in advance