A: 結婚したいけど、僕にはお金がないから...
B: お金なんか要らないわ。あなたといっしょにいるだけでいいの。
They are printed in bold. I dont really have problems understanding the sentence. But I wouldn't know what nuances are brought in by the elements in question.
The first に just indicates existence/possession in this case. I think that grammatically this kind of construction is called something like passive periphrastic (EDIT: no it's not. See comments). For example, literally you would translate it as "to me is (not) money", which means of course "I don't have money".
Consider also this simple example:
私には彼女がいます。
Which means obviously means "I have a girlfriend" although literally it would be "To me is a girlfriend".
So, to recap, you can think of に as usual as a "pointer". And do you remember the general rule that when indicating existence with ある・いる these verbs want the particle に? It's the same thing here as you are basically stating that "there is (not) money", where? "to you".
Regarding わ, it is just something similar to よ that as you knows adds emphasis to the sentence. The difference is that わ if I'm not wrong is used mostly by females. Also, I think it is quite used in Kansai dialect.