The sqeal is usually caused by the mike activating rx and tx at the same time. Could be a short somewhere. Or if it doesn't switch the RX off when you key up allowing the radio to be in rx and tx mode at the same time.
250hz off for voice is no big deal.
The amateur rigs are usually more accurate for more than just being an expensive rig, but they can also operate CW, which requires a near spot on accuracy. I wouldn't worry about that, the radio will drift more warming up than 250hz.
these radios are tried and true, the circuit they use has been around for a dogs age. So long as no one takes the golden screwdriver to it, you will get great reports. Also keep in mind if you are aiming to shoot skip, 12w PEP on SSB is all you need. You can have all the power you want, but if mother nature wont play nice with your signal, you wont get anywhere. When your shooting skip, you are at the mercy of mother nature, so if conditions are favorable, 12w is lots. I have done 1500+ Km on AM before. Rare, but if mother nature plays the cards right, it can happen.