Actually it all depends upon you that which wallet you use .
If you are using the official wallet of the bitcoin that is blockchain then you can see the address that always goes changes after one transaction so if you will send from.your wallet to the blockchain then Ofcourse no one will be able to trace your payment .
but if you are using the wallet that have single address ( doesn't change time to time and also dosen't change after transaction usual case of the mysellium , zebpay , xapo , coinbase ) Then I this case anyone can you easily .
But if you have one wallet that have variable address then you don't need to worry at all , Because no one can.trace you .
No this is wrong. The 'official' as you said wallet is not blockchain but the full node desktop wallet Bitcoin Core. Furthermore although it's a good practice to use new address for every transaction, also it is wrong that you are safe because bitcoin is not untraceable. There are ways somebody can find your wallet knowing only one address of it. As an example would you like to test it by your self using this site?
EDIT: Sorry, I didn't notice that someone two posts above my post had already said about the wallet explorer.