First sentance - is this correct?

[Eltu Siyu]

Oe za'u ftu alìm.
I come from far away.

Is this correct? I've been debating whether I need any prefixes/suffixes etc. 

Irayo!

[Carborundum]

You have a bit of a problem with your adjective there. Namely, it's not an adjective at all. Lìm, as per the dictionary, source Frommer himself, is a verb. How exactly "far" would be used as one I have no idea, so I can only assume the translation is an approximation for something English has no word for. Also, even had it been an adjective, adjectives need to modify a noun, which you have none. You want it to be an adverb, for which you use nì-. I don't think verbs can be adverbified, unfortunately, so we need to find some other way to say it. How about oe za'u fa ngima fya? Pretty convoluted, I'll admit, but if there's a better way there will be someone here to correct me momentarily.
About the suffixes; you don't need them, because "come" is not transitive.

[wm.annis]

You want it to be an adverb, for which you use nì-. I don't think verbs can be adverbified,

They can, actually.  We have nìtam enough from tam suffice.

Even if lìm is a verb, we can have it describe a noun using the attributive particle a.  It seems prudent here to be explicit, and use the word tseng(e) place.

  oe za'u ftu seng a lìm I come from a place which is far.

Note that the adposition ftu causes lenition of the following word, giving us seng from tseng.

[Carborundum]

They can, actually.  We have nìtam enough from tam suffice.

That's good to know.

Even if lìm is a verb, we can have it describe a noun using the attributive particle a.

!!!
This is awesome! The flying ikran is ikran a tswon. This makes things so much easier. And it's... so obvious. Oe skxawng lu. Seiyi irayo!

[wm.annis]

This is awesome! The flying ikran is ikran a tswon. This makes things so much easier. And it's... so obvious. Oe skxawng lu. Seiyi irayo!

Please banish *tswon from your vocabulary.  It really is tswayon, and the future really will be tswayayon.

And we have a variant form of this available to us: participles, formed with the infix ‹us›.  These act like adjectives.  Frommer gives these two examples:

Palulukan at‹us›aron lu lehrrap. 'A hunting thanator is dangerous.'
Palulukan a teraron lu lehrrap. 'A thanator that's hunting is dangerous.'

The meaning is basically the same.  As a stylistic matter, I sort of prefer the second form. 

[Carborundum]

Please banish *tswon from your vocabulary.  It really is tswayon, and the future really will be tswayayon.

Are you kidding me? Didn't we go from tswayon to tswon? And now we're back at tswayon? Sigh...

And we have a variant form of this available to us: participles, formed with the infix ‹us›.  These act like adjectives.  Frommer gives these two examples:

Palulukan at‹us›aron lu lehrrap. 'A hunting thanator is dangerous.'
Palulukan a teraron lu lehrrap. 'A thanator that's hunting is dangerous.'

The meaning is basically the same.  As a stylistic matter, I sort of prefer the second form.  

Ah yes, those things   Haven't really gotten around to them yet, to be honest. I suppose now is as good a time as any to do it.

[Eltu Siyu]

Dear me, I do have a lot to learn  

My original sentence was to be "I have traveled a long way". I have had trouble finding out words such as "traveled" and "long" so i replaced it with the sentence above.
I'm still rusty on my terminology so apologies for any misunderstandings. I'll look into things such as lenition and adverbs etc.

I like both corrections "oe za'u fa ngima fya" and "oe za'u ftu seng a lìm", but I understand the second better than the first one.

Irayo very much for the corrections and information. I never knew of lenition before. I shall keep an eye out for it in the future 

[wm.annis]

Dear me, I do have a lot to learn  

Slow and steady wins the race. 

My original sentence was to be "I have traveled a long way". I have had trouble finding out words such as "traveled" and "long" so i replaced it with the sentence above.

Ah, but we do have a word for "travel" now — sop.  I think nìlìm would work well with that.

[Eltu Siyu]

Ah, but we do have a word for "travel" now — sop.  I think nìlìm would work well with that.

I did no see that! Irayo! So "I traveled far" would be something along the lines of "Oe s<am>op nìlìm" ?

[wm.annis]

IS IT TSWAYON OR TSWON???!!!!

It is tswayon.

PERSONALLY I THINK IT SHOULD BE 'TSWAYON' BECAUSE 'TSWAYON' CANNOT HAVE THE FUTURE INFIX BECAUSE INFIXES GO STRAIGHT AFTER THE FIRST CONSONANT IN THE PENULTIMATE SYLLABLE!

Ahh... this is important.  Some early material about Na'vi talked about infixes coming after consonants, but this is misleading.  Verb infixes don't come after anything — they go in front of the vowel or pseudovowel of the syllable.  So the future of tswayon is tsw‹ay›ayon.  And the future of a verb with no consonant at all in the penultimate syllable omum has the future ‹ay›omum.

[NeotrekkerZ]

You want it to be an adverb, for which you use nì-. I don't think verbs can be adverbified,

They can, actually.  We have nìtam enough from tam suffice.

Even if lìm is a verb, we can have it describe a noun using the attributive particle a.  It seems prudent here to be explicit, and use the word tseng(e) place.

  oe za'u ftu seng a lìm I come from a place which is far.

Note that the adposition ftu causes lenition of the following word, giving us seng from tseng.

Is there a typo in Taronyu's dictionary?  It lists ftu- not ftu+.  I know fpi causes lenition...