Regarding aircraft approach categories, here is the quote from the US AIM. FWIW, my Bonanza falls in the approach category B:
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a. Aircraft approach category means a grouping of aircraft based on a speed of VREF, if specified, or if VREF not specified, 1.3 VSO at the maximum certificated landing weight. VREF, VSO, and the maximum certificated landing weight are those values as established for the aircraft by the certification authority of the country of registry. Helicopters are Category A aircraft. An aircraft must fit in only one category. Pilots are responsible for determining and briefing which category minimums will be used for each instrument approach. If a higher approach speed is used on final that places the aircraft in a higher approach category, the minimums for the higher category must be used. Approaches made with inoperative flaps, circling approaches at higher-than normal straight-in approach speeds, and approaches made in icing conditions for some types of airplanes are all examples of situations that can necessitate the use of a higher approach category. See the following category limits:
1. Category A: Speed less than 91 knots.
2. Category B: Speed 91 knots or more but less than 121 knots.
3. Category C: Speed 121 knots or more but less than 141 knots.
4. Category D: Speed 141 knots or more but less than 166 knots.
5. Category E: Speed 166 knots or more.
VREF is the reference landing approach speed, usually about
1.3 times VSO plus 50 percent of the wind gust speed in excess of the mean wind speed (See 14 CFR Section 23.73). VSO is the stalling speed or the minimum steady flight speed in the landing configuration at maximum weight (See 14 CFR Section 23.49).