I use a custodian wallet for transaction and don't re-use any address.
Using a new address for each transaction is highly recommended for better privacy but it becomes kind of pointless when using a custodial wallet!
If I want to get my first address back. How many time will I click so that I will get back to the first address.
If they are using HD wallets (which I believe they do), then it doesn't matter how many times you click the
reload button. The chances of regenerating the same address is almost zero.
Besides, their system won't allow you to generate more than 20 unused addresses. Probably, they set this gap limit so they don't have problems when calculating your total balance.
Or had any address that past has past. If yes. What of If their is matter that they want me to generate that particular address back from my wallet. What will I do?
You don't have to worry about this. All generated addresses belong to your wallet and any coins sent to one of them will be credited to your account.