How to make totally secure Bitcoin transactions? So, I'm wondering if my system of protecting my bitcoin is totally secure.

If I have an old laptop, and I boot into tails linux from a flash drive, and download electrum on there, and only ever connect to the internet at my home WiFi, and only ever visit Coinbase (GDAX) and Gmail, are their opportunities to steal my bitcoin?

Is there hardware risk? Would I need to wipe the drive completely, or can I purchase a hardware wallet that transacts without connecting to a laptop?

Is there WiFi risk, or are Electrum, Coinbase, and Gmail all encrypted connections so it wouldn't even matter if there were a man in the middle? (am I confusing things here?)

Is there risk with Electrum? Should I download the core Bitcoin client instead?

Obviously no cameras or microphones in the room when you use the dedicated laptop, right?
The primary concern with Bitcoin security is where your private keys are stored. 

In your scenario the private keys are stored on a Linux laptop which is not unreasonable if you follow good internet hygiene and security practices.

The next best approach is to purchase a hardware wallet from the likes of Trezor or Ledger. These wallets have High Security Module (HSM) chips inside them that are highly resistant to being compromised. By highly resistant it means the private keys are stored on a tamper-proof chip and NEVER leave it. The HSM chip in the Ledger Blue is ST31. Google for ways to compromise the ST31 versus ways to compromise Linux and you'll get the idea. 

With a hardware wallet it works in conjunction with a client on your PC but the crucial factor is the transaction (tx) is signed in the HSM chip and the only thing an attacker could do is try and replace the Bitcoin address in your tx. Most hardware wallets safeguard against this by displaying the recipient address on the screen when requesting verification of the signature operation.

And finally you could write your private key down on a piece of paper and hand-sign all your Bitcoin tx's. No electronic compromises to worry about.