It's exactly how you described it, you still can receive funds into your old addresses however it's highly recommended to use the new addresses, It's mostly a privacy matter so people will find hard time to link everything back to you.
Ok, perfect!
I found a iOS wallet called "Alta Wallet" (a desktop wallet is available too), which supports Bitcoin, Ethereum, Litecoin and Dogecoin, has a built in exchange and you can create multiple wallets (not just multiple addresses) So you can have like a wallet called "mining" with BTC, ETH, LTC etc. and a wallet called "donations" with BTC, ETH, LTC etc. and you can easily switch between them!
Pretty unique...
https://itunes.apple.com/us/app/alta-wallet-bitcoin-wallet/id1154367060?mt=8Have you ever tried it?
I took a look at Alta Wallet just to see if the wallet is good and or legit. Unfortunately that app isn't open source so there's no way for me or some people to know if they're doing something fishy or not. I honestly can't recommend it since this is the first time I've heard of that app, so maybe think twice into sending/importing all your bitcoins to that wallet. I think the chances of it being a scam is low though.
Take note that multi-currency wallets I think are usually(in my opinion) less secure compared to wallets that support only one cryptocurrency. Just a heads up. Try out Copay on your iOS device. It's the bitcoin wallet I've been using since forever; it also has multiple-wallet support like you described, and it's open source, so we know for sure nothing fishy is going on in that wallet.
