Most of it is necessary though some of it is probably so common you needn't concern yourself with it. I believe 99% of AC units for the home are single-phase, frame 48Y, and if they're not OEM they're probably reversible.
- 825 RPM is a common RPM. There are some RPM motors that are 1100. If you put a 1100 RPM motor in an 825 RPM you risk triggering the overcurrent protection.
- 1/4 HP is a measure of the watts the motor takes. 1/4 means it'll draw 186 watts of power. If you get a 1/5 HP motor it will only draw 149 watts of power, which means you have potential for undercurrent or not having enough power from the motor to push the fan.
- Frame 48Y is the motor type. I'm not 100% sure you can get an AC motor that isn't Frame 48Y for a condenser fan. All the ones I saw had this.
- PH1 means it's single phase, most residential AC units are single phase.
- FLA 1.4 means full-load amperage, that's the draw at the rpm/voltage/hp.
- MFD of the capacitor is also very important. This fan in this picture requires an 10 MFD cap. I replaced it with a fan that needed a 5 MFD cap. Because of this, I bought a 5 MFD cap and left empty the taps on my dual-purpose cap for the fan. Note on AC Capacitors I always buy 440 volt. But you can if you wish go down to the required voltage the fan needs and save a dollar or two. You can oversize on voltage, but your MFD must be +/- 20% (but seriously for the <$10 just buy a new one that's proper 440 at the rated MFD).
- CCWLE is counter-clockwise. In theory, you can find a fan so cheap that it's uni-directional and spins the wrong way. However, most fans that aren't OEM replacements seem to be reversible. And most OEM fans that are uni-directional seem to be counter-clockwise.
I would be mostly concerned with HP, RPM, and the capacitor rating/mfd.
I believe the rest of the metrics are probably very common: single-phase, 48y, FLA (probably runs static with HP and RPM), reversibility.
In addition, check to see whether the fan is 3-wire or 4-wire. It's not hard to move from 3-wire to 4-wire, but it is slightly more work. You can see on the connection diagram sticker the fan in the question is 3 wire. I replaced it with a four-wire fan.