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Yes, the lower the focal length of the eyepiece, the more magnification it gives. To work out the power, divide the focal length of your scope by the FL of the eyepiece. So you get 650/2.3 = 282x. For comparison a 20mm ep gives 650/20 = 32.5x.
You may read that a scope maximum practical magnification is 50x per inch of aperture, which in your scope gives 5" x 50 = 250x, but this is largely a theoritical limit. It requires exceptinal seeing conditions, near perfect optics and near perfect collimation to be even remotely possible. In most conditions it is more like 10-15x per inch, so I wouldnt use much more than 50-75x in your scope most of the time. So a 20mm and 10mm ep should be fine. The thing is that the atmosphere interferes with the image, causing it to move and jump (that's why stars twinkle). Higher power magnifies this effect, deteriorting the image.
Again, in your original post you mentioned issues with the supplied eyepieces. Were these actual issues you encountered or were you inferring them from reviews you read? Always treat online reviews with a grain of salt. I have come across some that were not worth a knob of nanny goats pooh! (to use an old friends expression!) It costs someone nothing to put up a review on line and there is no guarantee that the reviewer even knows what they are talking about.
Usually the EPs supplied with thsi class scope will be ploslls. They are generally OK and the low power ones are quite acceptable for beginners use. Premium EPs can be expensive so don't rush into buying them until you know what you are doing.
Malcolm
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