assuming you hit the private key can you share a method or a secure way to get these coins without double spend
Let's say you found the private key, the first step would be to change the Private key Hexadecimal format to WIF. And you DON'T want to do this with an online tool, all has to be done from your PC.
For this, you can use the "Bitcoin Address Utility"
https://en.bitcoin.it/wiki/Bitcoin_Address_Utility or any other tool.
$ bu YourHexPrivateKey
Then, you can import the WIF private key to a wallet like Electrum, or an online wallet like Blockchain.com But i hardly recommend to do this under a Linux Computer, if you want to do it from Windows there could be some risks.
which is faster to get confirmation
sending to segwit 3
or to legacy
appreciate any help and advise
The speed of the confirmations is based on the fees you use and not on the type of address. If you want a fast confirmation then verify how much you need to pay to have a confirmation in the next block, for that you can use the next site:
https://mempool.space/ Right now 58 sat/vB is a high priority.
And about your double spend fear, there is no way someone else double spend the coins if they don't have the Private Keys.