Yes, the C of G position will affect the stall speed a small amount, Some flight manuals do present this data. That said, for the one or two knot difference, it's a nice target for approach speed precision, but rarely do I see a GA plane flown to within one knot of the target airspeed on approach. If you can, certainly do!
As my colleague mentioned, unless otherwise specified, stall speeds will be presented in calibrated airspeed, rather than indicated. Some flight manuals offer the courtesy of presenting it in both. Otherwise, this is a common error, a pilot believing that a stall is immanent based upon knowing Vso, but not as a CAS value, and watching the airspeed indicator to see it.
If you're using an after-market AoA system for very precise approach speeds, okay, but there are a few things to be certain of before you believe it 100%. You must determine if it was set up correctly. Two important factors really affect this: Does the plane have any modifications which affect lift (Gross weight increase, STOL kit, VG's, Wing extensions, for example)? If the plane does, the stall speed has probably been affected, and further, the relationship between IAS and CAS may be different, or, if the plane stalls more slowly, there will be a need to have IAS to CAS conversion for the slower speeds, which may not have been provided. This is extra important if there are multiple "lift" modifications, as the resulting stall speed will be a combination of the effects of the mods, and it will be very unlikely that there's an applicable IAS to CAS correction table. And, when the set up was done with reference to the airspeed indicator, was it recently calibrated? Kinda pointless if it was out!
Then, once you have determined the configuration of the plane (in terms of mods), and the availability (or not) of IAS to CAS correction for that exact configuration, you need to verify that the AoA was set up correctly. I have set up a few planes with an after-market AoA, and it was not trouble free. The manufacturer's instructions were unclear about the use of IAS vs CAS for the set up procedure. When I chose to make the required calculations based upon CAS, it was not possible, as each of the planes had wing mods, so the stall speed was slower, and there were no POH, nor flight manual supplement IAS to CAS correction tables for those slower speeds. So I set the planes up to the POH values, as it was all I legally could use, but it made the AoA system [conservatively] not as accurate as it could be. And, even the AoA system manufacturer states that the system may not be used for primary speed reference, in place of the original stall warning, nor for increased capability (slow approaches, shorter landings) - so it's really for entertainment only once you turn final.
My best (and very experienced) advice is to use the values in the POH, and expect the performance stated there. If the plane has mods, look for flight manual supplements. If there are multiple mods, and no one flight manual supplement provides information for that combination, you have been left with inadequate data to fly the plane (don't worry, you're not the first). When I approve airplanes (by STC) with combinations of mods, I do the testing and provide the flight manual supplement to support exactly that configuration.
A last word of wisdom, if you're flying a plane with wing mods which reduce the stall speed, continue to fly Vy climbs, and approaches at the POH speeds, to prevent being too slow in the event of an engine failure. Even if you're flying a glide approach, the fact that the wing has been modified to give you more lift (or you're seeing that on an AoA) will not give you any more reserve of energy in the flare. Roberston STOL Cessnas are famous (and the Roberston FMS warns) for pilots getting too slow on final, and not having enough reserve of energy to flare. If you're between 500 feet AGL, and he flare, you are most safe at either VY or "best glide" speed, at the slowest.