When i send btc, i have to make sure the address is correct... triple check it many times before i click send. Obviously everyone should be doing this.
Yes, that is good practice... especially if you're copy/pasting addresses, to avoid issues with clipboard malware.
But if you make a mistake somehow with a letter off or accidentally deleted a character like m and put n instead... yes i know you should be copying/pasting the seed and never type it.... but obviously it could somehow happen if you accidentally type in an extra letter or deleted a letter by accident and replaced it by another character... what typically happens?
The wallet software detects the address is invalid and displays an error. Nothing "bad" happens.
I heard the odds of it being sent to another address was almost impossible... is that correct or not?
Correct.
Like could you be off a character... and that btc address is actually a btc address? Thus you woulda sent btc to someone else by accident?
No.
Obviously when you deal with big amounts, besides being very careful the address is right and the amount is correct... is make sure you are sending it with the recommended sending fee right? I can't imagine someone sending something like 5 btc... then pay like the minimum sending fee on their nano ledger s?
Why not?
If you're not in a hurry, sending with a minimum fee is fine... the fee rate used has no bearing on the "security" of the transaction, nor whether you entered the correct fee, nor the value of the transaction... if you're not in any particular hurry for the coins to arrive at destination, you can send with 1 sat/byte fee.
If you need the funds to arrive quickly, using a "good" fee for the current network state is always recommended... regardless of the amount being transacted.
If you're concerned, use RBF so you can increase the fee if needed.
Also, stop using bold font everywhere.