Need help verfying the specific cleaning and transfering process will work with iphoto

Alright to start of with an oversight this is a very sensitive issue as my 19 year old sister died in a car accident several weeks ago and one of the most precious things we have is photos and videos. So I feel I have to double check my steps here before I delete most of the content off of iPhoto to free up space on the computer to work on more projects.

I have 6 or 7 external hard drives, some new, some old, but most of the important content is going on to one of two LaCie 3 TB hard drives . A lot of content has been poorly organized in the past and thrown on these devices (with only the Lacie ones being organized properly) which is usually fine aside from the fact that programs like iPhoto can greatly complicate the process.

I don't like iPhoto that much for one main reason and it's how it packages up everything into a separate database that is difficult to work with. I am also learning Lightroom and love it as it runs much more smoothly and doesn't package everything up that way.

On this computer it says there is 492gb of photos which means half the total space is being taken up by these photos. 475gb of the photos are supposedly in iPhoto library. Yet from inside the iPhoto App when nothing is selected under photos tab it says 343GB. So were is that remaining 132gbs?

So far I have

-Exported all selected Events in the library as "original" and had it divide everything up by event name within a folder on the external hard drive.

(creating one folder with a bunch of subfolders)

-Then I created a smart album in iPhoto and singled out all edited photos. Then exported all edited photos using "current" into another folder on the External Hard drive.

-Copied and pasted the trash bin within iphoto to another folder on external hard drive. (these are likely junk or duplicates but with 33,000+ pictures that I can't look through all at once I had to be sure a least one Jpg copy existed of each. I figure that is easier to reference and delete accordingly using finder)

Now I tried to select everything but the last couple of months and delete them off the library but it says it will also delete photos off of Facebook. Now I've never used the integrated iPhoto/Facebook but my mom has and honestly when I saw that I just instantly felt mad and annoyed that was even possible. Maybe it's more common than I had thought but anyways I just want to disconnect that so I can delete the photos without it doing anything to facebook. There should be a button that does this but the only 3 options I have discovered so far is

-Change password and log out of facebook in the browser

-turn off the internet while deleting the photos

-press the minus button under account in preferences.

All of which has me paranoid that it will screw with my moms facebook and delete those photos.

Any help or verification would be greatly appreciated, thank you!