Can not seem to find last four spaceship parts

You can save manually by choosing the phone(UP on the D-Pad) and then chosing the save function.

To load, go to pause menu, game, load game

You have up to 15 save slots. You also have the option to copy a saved game to another slot.

For the Bail Bond missions in particular, and probably other missions you may want to track, you can view your progress by signing up with Rockstar Games Social Club and linking the account you're playing with.

In the Social Club page for GTA V, you can view your Career, and a tab under that category labeled Checklist will allow you to see all your progress in various missions. Maude's missions are under the Hobbies and Pastimes section.

This will only tell you whether you have completed the mission or not, though. It does not indicate where the target is located, and unfortunately this information does not appear on the Random Events and Strangers map at the bottom of the Checklist page. I suspect that the map could still be helpful for you to find other sidequests and events you haven't played yet.

As far as I know, there is no way to get back the emails or texts with mission information once they have been deleted (I'm kind of surprised they can be deleted; disappearing spontaneously would definitely be a bug). Resorting to a guide may be necessary on that front.