Q1: Can I use a 2 power or 3 power barlow lens to double or triple the magnification of this zoom lens ? If so, will I loose much image quality ?
A: The Zhumell 1.25 Inch 8-24mm Zoom Telescope Eyepiece can be used with a 2x barlow lens but a 3x barlow is not recommended. A barlow lens will cause the image to lose quality because the light is processing through another thick piece of glass. The distortion will be minimal but it is noticeable.
Q2: Just wondered if this zoom eyepiece would work on my Meade ETX 80 telescope?
A: Yes, since your ETX 80 uses a standard 1.25" eyepiece it will work just fine.
Q3: Will this fit a NexStar 4SE?
A: The Zhumell 1.25 Inch 8-24mm Zoom Telescope Eyepiece will certainly fit the NexStar 4 SE.