Because what I basically want to achieve is to be able to send/receive BTC no matter the API. I mean they can't limit number of requests if I use just a blockchain network right? I won't use any blockchain.info API, I will just access my wallet with a key I own throught the network and nothing else. How could they limit that? What am I missing here?
I think you've crossed a couple of wires someplace.
A wallet service, like blockchain.info and coinbase allows you to send and receive bitcoins. Your public key allows you to receive bitcoins, this is the address that you provide to people that you want to get bitcoins from. Your private key is something that you want to keep to yourself and not share with anyone. The bitcoin private key is universal, you can typically import it into any bitcoin wallet. This is important because let's say, blockchain.info shuts down tomorrow, you can just import your private key into another wallet and reclaim any bitcoins you may have. Be very careful with your private key.
Both blockchain.info and coinbase offer API services, this allows you to use code to access your wallet to send/receive/sign bitcoin transactions through code.
Both of them have limits in how you interact with the bitcoin network, this is to prevent bad actors and others from abusing their network.
With
your own wallet installed on
your own system, you can all of the above with
no limitations.
You might want to learn more about bitcoin on a technical level, there's a video series here that's free (only the mining video is outdated):
http://bitcoin.cbtnuggets.com/I'd be happy to skype with you at some point if you're still confused and I can walk you through some more information if you're still confused, just PM me.