Yes, the excess contribution penalty for 2018 calculated on Form 5329 will propagate to 2018 Schedule 4 line 59, so Schedule 4 should be included with your mailed 2018 amendment. (Form 5329 can sometimes be filed stand-alone since it has a signature block, but in the case of reporting an excess contribution I think it's appropriate to do a complete amendment to explicitly show that this results in no other changes to your tax return.)
If you want to use 2018 TurboTax to prepare the amendment you would have to duplicate your 2018 tax return in 2018 TurboTax, then prepare the amendment. It would be far simpler to prepare your amendment manually since the only changed amount will be on line 10, "Other Taxes."
The amount of your previous overpayment (your refund) will go on Form 1040-X line 18, so the result will be $330 on line 20, the amount you'll owe with the amendment.
