There are two parts to your question
- Factory Reset.
a) Factory reset removes user data including apps installed by the user on phone. Since your device is rooted, you can see that everything in /data
and /data/data will be wiped.
b) Factory reset does not flash stock ROM. Since you have deleted preloaded apps, they will not be restored. If you want them restored, you have to flash stock ROM
To understand more about factory reset, please read this
Factory reset to restore performance? What are the disadvantages?
- Root. You will not lose root on factory reset. Your phone will remain rooted
Please read this post to understand more Can I safely do a factory reset without losing root?
Further, unrooting will also not being back deleted apps
Please read this Will un-rooting return stock apps
Additional Information on reverting to stock ROM (asked by OP in comments)
How can I flash stock ROM?
Source for downloading Stock ROM: Sammobile, you have to register and download ROM specific to your model and region. You can check here also Where can I find stock or custom ROMs for my Android device?
Flashing Instructions: Can be found on many sites. Here is one such link (also having stock ROMs) from XDA. You can also see "additional information" of my answer
