Thank you! I'll get right on that gah-notu one :3.

My comments all messed up. Here it is correct (btw I tried editing it, something's wrong with the japanese):
 

Gah-notu: がのとぅ then seems the best way to translate it phonetically, as が is the same character used in the word gun and ‚の is the same character used in "knot". Japanese writing is highly innaccurate at portraying roman characters sometimes though, for example smith is translated to "sumisu".

 Pronounced "Guh" - "knot," like the verbal guh noise, then knot as in tying a rope. Aha

If it's pronounced "Gu-No", then the phonetic spelling is: ぐの. If it's pronounced "Gu-No-T", (gu-note) then the phonetic spelling is: ぐのとぅ. I'm not the best at Japanese, there are the phonetic ways of spelling 'em ;).

 I've been told that Gniot literally means "Piece of bone" by my uncle who's done extensive research into the etiology of our last name. Is there any way I could go about finding the translation of that, but into a last name form? I hope that makes sense. 

I think 'ponkotsu' is japanese for junk.  So its not pronounced like your name, but has the same meaning.  Translating phonectically means writting it how it sounds, not according to definition.  If you want to write it phonetically something like 'gu' 'na' 'to' might be the closest.  I dont have japanese characters enabled on my compter right now so youll have to look up what those look like.  'gu' is the same character as 'ku' with 2 dashes in the upper right corner though.  And a circle in the corner makes the 'H' characters into 'P' characters.

 What exactly is the meaning behind the phonetic version? Since it is my last name, I'd like to know as much about it as you could tell me :)

Yes, if you are going to translation by meaning and not phonetics. Just the circle on the hon is fine. 

 Pronounced Guh-not, I find that rather funny that the etiology is "Piece of Junk." I may incorporate that into a future piece or something :). So, to fix this one, I just need the circle on the "hon?"

This reads "Honkotsu" Gniot would be "Guniotsu" and ぐにおつ in hiragana, グニオツ in katakana.
Tho it really depends of how you pronounce your name. If the G is silent, if there are stresses somewhere and so on.

EDIT: Just checked. It translates it to PONkostu, you forgot the maru (circle) thingy on the hon ぽ not ほ. Ponkatsu means "piece of junk" and it seems gniot is polish for just that. What an unfortunate last name.