There is a Hole in my Promise

I promised I would not make anymore Riley Riddles...
...I failed to keep it.

Riddle me this:

My prefix and its prefix, are each an animal.
They fly, but one will only do it if impossible.

My suffix in a sandbag, will only make it lighter.
The food my prefix eats can be a prefix, too, for hire.

My suffix is a billion, and much older than you.
It's in my prefix, second half, but with N it is 2.

I have a principle and letters are superior.
My name has words of two, my first a prince by Warriner.

What am I?

This time, I tried to squeeze in as much information as I could, and I think this might prove to be an interesting one, unless you are tired of Riley Riddles (sorry @Level51).

The title is a clue.

Hint:

The word has $$10$$ letters... but that's not the only hint.

• The prefix has a prefix？ – PotatoLatte Sep 22 '18 at 13:59
• @PotatoLatte yes. See here, for example, if you don't know what I mean :P – Mr Pie Sep 22 '18 at 14:17
• Since it's already solved i was wondering what did the bold and the italic parts hinted towards. – Shahriar Mahmud Sajid Sep 23 '18 at 5:55
• @ShahriarMahmudSajid oh, I'll tell you in Rot13: $\ast$ Gur obyq "j" naq "b" ersref gb gur svefg gjb yrggref bs "jbezubyr", jurer "jbez" vf gur sbbq gung cvtrbaf rng. Nyfb, geniryyvat guebhtu n jbezubyr vf gurbergvpnyyl geniryyvat snfgre guna gur fcrrq bs "yvtug", urapr V jebgr gung va vgnyvpf. Naq nyfb, gur obyq "ov" ersref gb "ovanel". 2 va ovanel vf 10 naq gur 10gu ryrzrag bs gur crevbqvp gnoyr vf ARBA. Gnxr bhg gur svefg A naq lbh trg RBA. Nyfb, na rba vf n ovyyvba lrnef, naq jr zrnfher ubj "byq" jr ner va pbhag bs lrnef, fb V jebgr "byq" va vgnyvpf, gbb. $\ast$ And yeah that's about it :P – Mr Pie Sep 24 '18 at 1:28
• @Racso read my comment above if you have given up :D – Mr Pie Sep 24 '18 at 1:28

I'm guessing you're a

pigeonhole

My prefix and its prefix, are each an animal. They fly, but one will only do it if impossible.

Pigeon, Pig. "When pigs fly".

My suffix in a sandbag, will only make it lighter. The food my prefix eats can be a prefix, too, for hire.

Holes make sandbags lighter. I'm not sure about the hiring part.

My suffix is a billion, and much older than you. It's in my prefix, second half, but with N it is 2.

I'm not sure if I got this right. Here, I thought about "black holes" and "eons" (the time unit).

I have a principle and letters are superior. My name has words of two, my first a prince by Warriner.

There's a book called "The Pigeon Prince", by MR Warriner.

• Hi, this is probably the correct answer, and I can follow your thinking just fine, but explanation would be appreciated and is the standard policy on this site :) – Quintec Sep 22 '18 at 14:15
• This is correct, so well done on that! Also, (ROT13) ertneqvat gur "uver" cneg, lbh pnz irel pybfr gb fbyivat vg jura guvaxvat bs "oynpx ubyrf". Rirelguvat ryfr vf pbeerpg, vapyhqvat gur "rbaf" cneg. Great job! When would you like the tick? :D – Mr Pie Sep 22 '18 at 14:19
• Sorry, I was working on an answer. (If you don't believe me, I'll give you the link). I'm good now, so... Congratulations! $\color{green}{\checkmark}$ Do you want me to tell you the parts you are unsure about? – Mr Pie Sep 22 '18 at 15:30
• I'd like to try to understand them later, but please feel free to post the solutions anyway in case I give up :) – Racso Sep 22 '18 at 15:32