Excess 401k contribution - past deadline. How to correct (pt2)

This Q/A is super helpful in handling excess contributions that weren't withdrawn past the deadline. To summarize,

- Follow the instructions in the thread to mark the contributions as income for the impacted year

- It's ok to wait to actually withdraw and incur taxes until retirement

I have a couple of specific questions on this though;

1. Does it matter if this was a mix of pre-tax and post-tax contributions? e.g., should I not include the after tax contributions since they've already been taxed for the year?

2. For return of excess, the amount to withdraw is +/- the gain/loss on the contribution. Should I enter that amount as additional income on my tax form, or just the base overcontribution?

posted