Cant we make this.retrieveBalance independent of BlockChain.info ? I mean to say, the URL to be used will be in a config file and user may control whether it will be blockchain.info/biteasy.com/helloblock.io/blockr.io/his own blockexplorer URL running on VPS.
Yes you can. The main thing you need to be aware of is that when creating a payment you need to retrieve unspent outs and different services i.e. blockr.io vs blockchain.info have different formats for this.
I'm more than happy to look at pull requests for this or for BIP39. Makes sense to develop this all in one place.
Is it possible to make the source code independent of any third party API by having its own daemon running and fetching data from that ?