de or ni when suggesting an action
 

Hey guys,
I'm wondering about the use of 'de' and 'ni' (apologies for not being able to type in Japanese chars on this PC):

Example: Toshyokan ni hon wo kari ni ikimasu

Why is this not 'Toshyokan 'de' hon wo kari ni ikimasu.', since borrowing a book is an action?

Similarly, why is it:
Resutoran ni bangohan wo tabemasen ka?
rather than
Resutoran 'de' bangohan wo tabemasen ka? Since eating dinner is also an action.

Is an intended action treated differently from a current or completed action?

Thanks for your help,
Chesh

Because 「図書館に」 modifies 「行きます」 rather than 「借り（る）」.

Where did you find "Resutoran ni bangohan wo tabemasen ka."? It is incorrect. The correct particle is 「で」.

No, it is not. All that matters is the types of verbs, stationary (go, come, stay, be, etc. ) or action (the vast majority of all verbs).

Great thank-you, that has helped to clear up my confusion.