You should avoid using MultiBit... it is old, outdated, full of bugs and the devs are no longer developing or supporting it. It is effectively "dead".
https://multibit.org/blog/2017/07/26/multibit-shutdown.htmlBasically, you should NOT continue to use MultiBit, there is a very good chance you could "lose" BTC due to the bugs and the fee issues.
If you still have a MultiBit Classic wallet with keys, you should follow this video:
https://www.youtube.com/watch?v=LaijbTcxsv8(Note that in the latest version of Electrum, you should use: "Import Bitcoin Addresses or private keys" NOT "Standard Wallet" option)
If you have a MultiBit HD wallet with 12 word seed, you should follow this video:
https://www.youtube.com/watch?v=E-KcY6KUVnYAs for operating a website, with Electrum as your wallet, the easiest way to generate unique addresses for users, would be to use your "xpub" address (Master Public Key) and one of the bitcoin ecommerce plugins like Mycelium Gear or the CryptoWoo (WooCommerce plugin)...
That will allow you to generate an almost infinite number of addresses on demand. Due to the nature of xpub's, you can't generate the private keys from them, so there is little risk in putting these public keys into a plugin like Mycelium Gear or CryptoWoo.
The bitcoins would then go to your Electrum wallet that generated the xpub. Electrum also makes it relatively easy to send ALL your coins to one address later (you basically just click the "MAX" button).
