Some people with great difficulty and struggle manage to acquire a nice and feminine voice with voice training. I'm just wondering if doing ONLY Trachea Shave (without Voice Surgery) can make you lose your female voice and make it hoarsy permanently or something or leave a permanent visible scar...

It shouldn't do much to the voice at all, there may be some issues immediately post-op while there is still swelling though. As far the scar, it's generally fairly small and will fade fairly quickly.. If you have any creases on your neck, the surgeon will often 'hide' it in a crease.

Yes, loss of upper vocal range is a rare but possible complication from a tracheal shave. The goal is to shave off cartilage without touching your vocal cords; if the surgeon does their job well, your voice will fully recover post-op. If they make a mistake, all kinds of crappy things can happen. Luckily complications are rare, especially the very bad ones.

Yes, there is a permanent scar. It is usually placed in the fold where your neck reaches your jaw, or up higher underneath the chin. It is quite small. Mine is 2/3 of an inch long and invisible unless I tilt my head back.

My tracheal shave was done by Dr. Spiegel in August. I recovered my voice entirely in 2 weeks.

Depends on the doctor.

If she or he does it right, you'll have some harshness for a couple weeks. If your voice is very different then they done something wrong as they should not touch the vocal chords.

My voice was definitely affected.  It's less flexible now, and gets tired & scratchy by the end of the day. 
Also, the scar is quite visible.
I had this done in my late 30s by a prominent cosmetic surgeon.