Where can I find/buy Sifrei Nach with Rashi translated into English and (even better) the Rashi with nekudos?
The Judaica Press Nach series (with the pink and red dust covers) has every Rashi rendered into English. It does not vowelize the original Hebrew text of Rashi. (This is my experience, having used a few of the volumes. Make sure before you buy.)
The same translation is on
chabad.org, but in some (all?) cases without the original Hebrew text of Rashi.
Sefaria has Rashi with nekudos and translated into English
Metsudah has also put out Nach with Rashi with nekudos and translated.