Cool project silverjoel, unfortunately video resolution is too low to look at details, but it seems well done. Regarding blender and models, if you say there are models on the net already modeled and rigged in Blender format, I suggest you to use motorsep md5 exporter which it should convert properly.
And for using these models, you don't need to learn Blender, just remember that Blender uses right mouse to select (Ctrl Alt U to open preferences and go to Input tab to choose left mouse click for select), A key to select/deselect all, tab key to enter/exit edit mode, shift + f5 to go to 3d view, and shift + f12 to go to animation view (so you can see if those models are properly animated).
Then select model -> File -> export -> md5. Done!
For my experience, if you want to create a project, keep in mind you'll probably be on your own, so start learning modeling, texturing and coding.
PS:it's a shame Idtech4 never had the attention it deserved. It's more used quake1 engine than doom3 one!
Oh, for a modern version of idtech4 bfg engine, take a look at !