We need a currency and want to allow user to create account from UI and send/receive amount between wallet

Question

We are developing a blockchain base product for our own digital currency.We need a currency and want to allow user to create account from UI and send/receive amount between wallet.
                                      Currently in this system multichain is used as a blockchain network. To communicate with this network we used a nodejs wrapper and front end app in angularjs. As multichain network is supporting peer to peer network we setup locally a Multichain network on our two systems also setup nodejs on both systems separately on our local machines.

There are two different ways in our mind:  
 1. Use a regular database to manage users under one server and that server will responsible for communication with multiple or single node of  blockchain network for wallet management and transactions.but it becomes centralized we want decentralized. 

2. Other way is every user has its own blockchain network node on his local machine and desktop base app for wallet management. we do not use regular database for it.
 here are some question for this architecture...

How users data can be store for the system in better way on blockchain ? 
How mobile or web users can use our product ?
How we can improve security on this architecture ? 

Answer 1

These are several very complex questions. As a starting point you might also want to look into the use of external private keys, which allows each user to manage their own funds but without requiring their own node:

https://www.multichain.com/developers/external-key-management/

If you want mobile users to directly access the network, not via one of the nodes, you will need to develop an SPV wallet to work with your MultiChain network. You can start with an open source bitcoin one and then modify it as necessary.