Dannny pretty much hit up all the questions. Finding out which wallet is key. I hope it was coinbase.
But for others reading out there are hardware wallets you can use with mobile android with wallets like MyCellium. Ledger Nano and Trezor both work with it great. I really like the extra security of having a hardware wallet even when mobile. I don't like to store much more then spending money in my hot wallet accounts so even if was a loss is not a big deal in overall scheme.
I'm sure on "account #" he means his bitcoin address. Probley deals with fiat more in a fiat world you might look at something like it an account.