Itsuka = "Sometime, someday", and "iitakatta" = "wanted to say." Because of the prior line, this is more likely, "It has words that I've wanted to say to you (but couldn't, etc.)."
Your translation of "nanka" as "anything" or "something" is correct; keep in mind, though, sometimes "nanka" is filler and has no meaning.
tada chizu o hirogete
Here this isn't a command, but in the -te form to indicate that other connected actions follow. Also I'm thinking that "tada" in this case is more of "... but", or "... though", so this line and the one following are more, "... But I opened the map, but I waited for the wind. Finding not even answer, I'm going."
IMEEJI(4) no mukou
Hehehe, this is the super-fun part of Japanese -- words that are clearly English loan words that don't have QUITE the same meaning in Japanese. Though it's clearly "image," imeeji is ... wow, how do I explain this. Okay, if you look at a sale paper in Japanese, you may see an item with an asterisk by it, and the bottom text reads, "* IMEEJI DESU", indicating that this is perhaps a product mock-up and the real product doesn't look QUITE like this. So an image is something that has some basis in reality but doesn't QUITE sync up the way something actually IS. Does that make sense? This line is thus something like, "Towards what I want to be" or "towards what I dream of being".
You're quite right on "ka na" -- it's like a "... I think," or a "perhaps."
tada ame ni utare tada niji o matteta nda utagai mo sezu ni
Same as the above similar stanze. Here I believe "utare" is like a noun and NOT a command. "... though the rain beat down upon me, though I wait here for a rainbow, Without any sort of doubt I go."
no subject
On your translation:
itsuka iitakatta kotoba ga aru yo
Itsuka = "Sometime, someday", and "iitakatta" = "wanted to say." Because of the prior line, this is more likely, "It has words that I've wanted to say to you (but couldn't, etc.)."
Your translation of "nanka" as "anything" or "something" is correct; keep in mind, though, sometimes "nanka" is filler and has no meaning.
tada chizu o hirogete
Here this isn't a command, but in the -te form to indicate that other connected actions follow. Also I'm thinking that "tada" in this case is more of "... but", or "... though", so this line and the one following are more, "... But I opened the map, but I waited for the wind. Finding not even answer, I'm going."
IMEEJI(4) no mukou
Hehehe, this is the super-fun part of Japanese -- words that are clearly English loan words that don't have QUITE the same meaning in Japanese. Though it's clearly "image," imeeji is ... wow, how do I explain this. Okay, if you look at a sale paper in Japanese, you may see an item with an asterisk by it, and the bottom text reads, "* IMEEJI DESU", indicating that this is perhaps a product mock-up and the real product doesn't look QUITE like this. So an image is something that has some basis in reality but doesn't QUITE sync up the way something actually IS. Does that make sense? This line is thus something like, "Towards what I want to be" or "towards what I dream of being".
You're quite right on "ka na" -- it's like a "... I think," or a "perhaps."
tada ame ni utare
tada niji o matteta nda utagai mo sezu ni
Same as the above similar stanze. Here I believe "utare" is like a noun and NOT a command. "... though the rain beat down upon me, though I wait here for a rainbow, Without any sort of doubt I go."
Hope this helps clarify things!