From what I've been reading it should have 1-2 dB noise figure, and about 20 dB gain. The ones I'm looking at now are okay, but kinda noisy (and also very pricey!!!):

CM 7777 (2.2 dB noise - higher than I want)
Winegard AP-8275 (2.8 dB noise)

Also I'm trying to tune-in VHF 10 which has proven challenging (sometimes there; sometimes not). Would the preamp help?

Any amp with figures like that is going to be pricey, as in several hundred dollars. The 7777 is about the top of the "reasonably priced" heap.

The CM-4228 is a UHF antenna. It works OK for high VHF, but it has a lousy front/back ratio and not all that much gain. If your problem is multipath or co-channel interference or basically anything but a weak yet clear signal, a pre-amp will not help. A better antenna, designed for VHF, will help a lot more. Especially if you put it outside, on the roof.

A preamp will not help if the antenna isn't getting the signal in the first place. I'd suggest putting both your 4228 and an Antenna cut for upper VHF (deep fringe) outside on the roof, and THEN see if you need a preamp.

I got an antenna designed just for ch 10. You can then combine it with your UHF antenna with a joiner or better yet, the CM7777.