You may be able to simplify this considerably.
1) Install LibreOffice
It's free. It's similar to MS-Office. You'll create a presentation (the module similar to "PowerPoint" is called LibreOffice "Impress").
2) Add slide transitioins
After you build your deck (you can actually import PowerPoint slide decks if you have one) make sure you set automatic slide transitions. (You'll find slide transitions is an icon in the right margin of the user interface).
3) Set the slide show to auto-repeat
In "Slide Show" -> "Slide Show Settings" click the "Loop & Repeat after ____" and set some number of seconds.
4) Save the presentation
Give it a filename and save it (e.g. "File" -> "Save as...", etc.)
5) Test auto-launch of your show
You can launch the presentation so that it automatically starts running via command line. Open a Terminal and type
libreoffice -show my_presentation.obp (or whatever the name is for the presentation).
6) Configure the user-account to auto-launch the slide show.
Assuming everything works as you expect... configure the Pi to auto-launch the presentation as soon as the desktop launches.
You can configure the desktop to auto-launch an application by editing
Add a row to the end of the autostart file that looks like this:
@libreoffice -show /home/pi/Documents/Sample-Slide-Show.odp
7) Test it
Logout (Shutdown -> Logout)
Log back in
The slide-show should automatically launch and start playing within a few seconds.
If all of these steps work, then the Pi will autolaunch your slide show when it boots each day.
If you want to avoid the Pi's memory card becoming corrupted, you might want to create a cron job to shutdown the Pi each day when the museum closes.
sudo crontab -e
"cron" is a unix facility that automatically runs commands at periodic times. The "crontab" file (the "table" of "cron" entries) is the file that specifies what to do ... and when.
An entry that would shut the Pi down at 9:00pm each day might look like this:
00 21 * * * shutdown -h now
This command says at "00" minutes of hour "21" (9pm) on any () day-of-the-month and any () month and any (*) day-of-the-week, run the command "shutdown -h now" (shuts the system down with a "halt" and do it immediately (normally there's a delay).
By doing a system shutdown, all files are closed and processes and terminated so that there should be no memory card corruption. The Pi wont deprive itself of power (it doesn't have a way to do that) so someone will have to unplug them you can get power supplies that have a tiny on/off button on the cord.)