Need/Iru (..shi) nakerebanarimasen
 

One, I'm going to apologize because the place I'm at doesn't have japanese input >.> my bad for the romanji.

2. I was looking through my jisho! I stumbled upon iru (need)

If i wanted to use iru would i say

okane ga iru (i this implies the money is a living person XD)
or would i say okane ni iru?


3, I also saw in my jisho (shi-) nakerebanaranai (rimasen)
It says (need to) or be obliged.

I was curious how I would use that in a sentence, I've been practicing japanese more lately since my korean friend is fluent in japanese
and we hangout every saturday and sunday and I wanted to use a new phrases and sentences.

please help.

The verb いる as in 'to need' has a kanji. I'm not sure about the usage but I've seen it used by a variety of sources. As an aside, the kanji for 要る(to need) is also part of the compound 必要（ひつよう） which also means 'need' or 'necessary'. When I check a couple of places, all the example sentences use が　(in some cases, は, but you were trying to distinguish が vs. に). Also, I'm certainly not a native speaker, but something feels a bit odd about using に in お金に要る。

About しなければならない and all variations thereof, don't make the same mistake I did when I first learned it. It means 'have to' or 'must' do something, but you don't use it in all the same places we say 'have to' in english. Correct situations you would use なければならない, 'I have to turn in this paper', 'I have to do my homework' etc. I'm making this point because I used it incorrectly to mean things like 'I still have to watch this TV show' or 'You have to read this! It's so ridiculous!'. You'll figure out more what I mean through using it and seeing it used properly.

Must in Japanese has a special construction. Instead of giving an "order" positively, they use a negative form.
To make you understand I try to use an example. If I want to say "tonight I have to go to work" in Japanese I will say "If tonight I didn't go to work, it wouldn't be good". I am not sure about English, but it sounds good to my ears coz even in Italian (my language) we use "can't go" like they use it in Japanese to mean "it is not good". Apart from ikemasen (I don't know if you can read Japanese from that computer so I use the hated romaji) it is used also the verb naru (here negative narimasen). Mind though that naru doesn't mean only change. In this case it has more a meaning of "suit".

As per need, I have mostly found it written in hiragana and probably that's why it confuses you. But as Duo said, this iru has nothing to do with the iru=exist. Two different words.

EDIT: Hopefully you haven't read my answer yet :) I just noticed you wrote (shi)nakereba...
Well, nakereba is the conditional form of the negative particle NAI. Thus in that case is put after the verb suru (which in negative becomes shinai). If you use another verb, leave out the shi and use the negative root of the verb. So in my example above it would have been (to work=hataraku): hataraka-nakerebaikemasen.

I think Yuusuke could benefit from a simple breakdown of the grammar. Basically, the structure of it is:
Also note you can contract なければ into なきゃ, so you will often hear in casual conversation something like 食べなきゃ.
It does indeed mean "must."
行かなければならない = I must go.
行かなきゃならない = I gotta go!
etc.

I personally use ならない over いけない, but there's no real rhyme or reason why. As far as I know, they mean exactly the same thing in this situation. If there's a slight connotative difference, I don't know about it.

You're using the "right" one. It's mostly, if not entirely, kids that use いけない. If an adult uses it, it just won't sound very good. As for the meaning, they're the same.

Thanks for the note, Sashimister. I'm happy to improve my Japanese with this type of small note that fills in a gaping hole in my knowledge.

Now that KyleGoetz noted the contraction なきゃ for なければ, I think I should add なくちゃ in as well. I'm not sure about real life speaking, but in anime, manga, and drama, I usually hear/see this contraction, and the ならない / いけない part is often omitted. Can anyone explain the difference between なきゃ and なくちゃ, like who would use each of them? I only know the difference in the number of syllables, though.

Since all of the abbreviations seem to be thrown in here, I'll just add in the last one I can think of:

Neg+と

eg:
食べないと
読まないと
飲まないと
行かないと
etc.

なければー＞なきゃ
てはー＞ちゃ
ではー＞じゃ

My textbook says as follow:

Spoken language alternative forms of なければ are なきゃ and なけりゃ.