Base Forsaken aren't that worth using in later loops as Superior and other species Forsaken are better, but you cant even start getting Superiors until loop 3 let alone the other species, and even in later loops Base Forsaken are fine for just using their punisher effects. So feel free to train up your current Forsaken, though unfortunately I don't have any guides for Forsaken training and there are other people here who can do a significantly better job than me at helping with it.
As for Distortions, honestly if you can going for Distortions as much as possible is ideal, since the right Distortion on the right Chosen can make a pretty strong Forsaken, and even if the Chosen is useless for a Forsaken Distorting them is still progress towards the Distortion achievements and triggering the Distortions generally give a lot of EE (though I personally wouldn't recommend triggering Rampancy unless you want to use them as a Forsaken since it makes them extremely annoying to surround for the entire rest of the Loop).