=> When I load my wallet A still shows 100,000 (but the block explorer website shows less than this).
That's probably because wallet A includes multiple addresses, but in the block explorer you are checking a single address.
You are confusing wallet with address. Note that a wallet can include numerous addresses.
How can I send money to my original wallet (A) from my supposedly new wallet(X).
Address X is a part of your wallet and there is no need to make any transaction.
That will be used whenever you make a transaction.
and again if I send from wallet X to wallet A, will it not create another wallet (Y)?
Address X to address A. Not wallet X to wallet A.
Every time you receive a transaction, a new UTXO is added to your wallet.
Let's say you have received 0.1 BTC in transaction A and 0.2 BTC in transaction B.
Now you have two UTXOs.
UTXO A: 0.1 BTC
UTXO B: 0.2 BTC
Any of UTXOx must be spent completely.
If you spend all the fund, your wallet will use both UTXOs and there will be no change.
If you spend 0.2 BTC and only use UTXO B, there will be no change.
If you spend 0.15 BTC, you have to have a change address.