1) Yes, you still need to submit a Form 8606 for 2018 since that is the year of your contribution. It doesn't matter when you plan to take a distribution.
2) Form 8606 can be filed separately, so it is not necessary to amend your 2018 Tax Return. You will need to mail this form in as it cannot be e-filed.
Form 8606 should be mailed to the same address as a Form 1040. The mailing address depends on which State you live in. Click here and choose your State: https://www.irs.gov/filing/where-to-file-paper-tax-returns-with-or-without-a-payment.
