Setting up the initial first or the total first makes no difference. For a fully tuned distributor they both need to be done. Plus timing at idle and light throttle constant speed cruise are also important.

As for running bad with advance connected. It's probably pulling the plate and bringing the reluctor out of phase. This can be checked by drilling a big hole in the dist cap. Shrine timing light in the hole and check the rotor to tip alignment with and without the vac advance.

Ported and manifold advance is exactly the same except the ported offers no advance at idle.
Most engines if not all engine will idle better at
20-40 deg than at 8.

My engine idles smoother and I can close my throttle blades more when using manifold vac advance. Most high stall auto guys would never appriciate this but mine is a stick and I have more power at light throttle, in the very low rpm range (accelerating in 5th in the city).