A visual approach is a procedure all of it's own. There is no defined obstacle clearance provided and the pilot is responsible for deciding what track and level to fly at to avoid obstacles. The flight is still IFR unless the pilot has cancelled the IFR flight plan.
The US, ICAO and European rules agree on this point.
If you have to execute a missed approach from a visual approach then you fly the missed approach appropriate to that visual approach - as agreed with ATC.
Unless you want a surprise you should ask in advance what ATC want in the event of a missed approach.
If you have discontinued one approach procedure in favour of another then one can not rely on the missed approach being the same. -
The first words of the Visual approach definition - It is a procedure.
A Circling procedure is something that is done after completing an IAP in order to line up with the landing runway. It has a defined containment area and one can not leave the IAP until within this area otherwise obstacle clearance may be compromised.
Unless specified otherwise, the missed approach for a circling is the IAP missed approach - initial turn towards the aerodrome overhead and follow the MAP.
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9.G,
Performance A simply relates to the aircraft performance and it's ability to avoid obstacles. The criteria apply in both VMC and IMC, VFR and IFR.
Anyone can file an IFR flight to an aerodrome with no IAP. The flight has to be visual at the IFR minimum safe level in order to descend for landing since it has no procedure for getting lower. This might make operations impractical but not impossible. Some countries require IFR to be cancelled before descending below the minimum level and others do not.