Can I lose my NCO rank if I go from Army guard to active duty?

Yep, you sure can.

Don't know specifics your case, but, you need to consider that you have to meet the qualifications and there has to be a slot for you. I am a Marine veteran, all during my life I have seen service members move from service to service and lose rank in doing so. YOU are making the request and there may be opportunity for you but it will be in their terms. BTW, how are you making a move you don't fully understand before you do so?

Yes, when I came back active from the reserves I was reduced to SPC. Regs have changed since then and there are factors involved. But it is a definite possibility.

I dropped from E-5 to E-3 when I converted from Reserves to Regular Army.
Good news was I made it back within a year.

The old rule was if you went Active to RC then back again, you'd go active at whatever rank you went RC at. I had an NCO that was AC/RC at the school house and wouldn't go active because he'd go from E-6 to E-4. It's dumb but then, it's the Army

I didn't lose my E5 before going active

Yes. Active will take your stripes, either down to SPC or PFC. It's bullshit, because officers don't get reduced.

Yes, and most do or are knocked down one grade. Get WLC so you're promotable.

Yes you can, if they don't have your Mos, if they don't have a slot open with your rank and mos, if you agree to reclassify in an mos in your rank and you go to school in a year you could also keep your rank

Probably not. Perscom has established rules about that.