Is it possible to make it so dropdown box has "other" option and that option allows custom entry?

A dropdown box would have an "other" option. When other is selected, user inputs custom entry. When this is downloaded to a spreadsheet I want that custom entry to be in the same column as the other options in the dropdown. I do not want the custom entry to be placed in a separate column. If another (hidden) textbox is required for the custom entry it will be in a separate column in the excel spreadsheet, correct?

Unfortunately, I don't think that's possible. There is a workaround that involves conditions and a separate text box, but that isn't what you need because the text box value will be place in a separate column.

However, that downside can be mitigated by using Excel formulas to merge the text box value with the drop down value.

Hope this helps.