thanks very much for the response! Can you help me understand the concept of wallet backup? When should I go about doing that and what is the purpose?
When you first run the QT wallet it creates a file on your system called wallet.dat. Inside there is a bunch of private keys that generate your addresses in the wallet and control of those lets you spend. So the wallet.dat file is basically your 'wallet', you can go to another computer and restore your full wallet and history just with that file, which makes it pretty important to backup and secure.
The recommended process when first running QT (which generates your new wallet.dat) is to:
a) encrypt it first using a VERY strong password (like 20+ characters including numbers, capitals, !@#$%%^ etc) and backup that password offline (and don't save it cleartext on the same computer) . Option in QT menu is [Settings->Encrypt Wallet]
b) backup the now encrypted wallet to offline storage like some USBs. Option in QT menu is [Settings->Backup]
This way you have a backed up wallet.dat that's also encrypted, so if an attacker gets the file, they can see your public keys / history but can't spend
You can receive funds before the wallet syncs on an address created with the 'Request payment' button on the receive tab, but you can't confirm if your received funds until you have the full chain synced (and remember to encrypt/backup the wallet.dat before using any address for payments)
One caveat is, if you have a wallet that's used a lot (like 1000s of tx, mixing etc) you can run out of the keys that were generated when the wallet.dat was created. You get a popup warning if that happens, and if it does you need to do the backup process again, because new keys have been generated that the wallet will use automatically that weren't in the first backup. So for heavy-use wallets, need to back up regularly.
Last thing - most secure place to store Dash is a paper wallet or hardware wallet. Those would be more secure than QT (which is 'live' on your computer and can be hacked e.g. an attacker keylogs you typing in your pwd and can lift your wallet.dat). Hardware is better if you plan to use the wallet regularly, paper is easier / cheaper if you want to store funds offline for long time... options at the bottom of this page:
https://www.dash.org/wallets/#wallets
