Hi,
For question #1, try to change the gender of the father from male to female, and of the mother too, from female to male. Save your mods. Check the result.
About #2, I don't think there is a function to merge two persons only, but there is a tool to merge two gedcom files.
If you want to merge two persons, I guess it's because two persons may represent the same child of a couple. If so, it's simple. Simply add child #2 to familty of child #1. Delete chlid #1. This method is available only if you can delete without any lost child #1.
Of course, as usual, try those changes with a backup of your gedcom file.
A tip to know: Ancestris create a backup of your gedcom file, each time you save changes you may have done. The number of backups is a parameter in the config menu.
Hope that helps. Maybe someone else will have a better answer. Francois