Hi there !
I'm probably as much a noob as you are, given that I only have a few months with Eurorack.
That being said, if I was given your rack I would probably think about adding an effect module or 2, especially if you plan on using the input on that 1U module to get some external sound sources into your rack. Which one is entirely a question of choice. I'm having a lot of fun with the Make Noise Mimeophon, but it's just an example. For anything ambient, I'd say one would probably need a decent reverb, but again, that's just my very small experience making the occasional ambient patch on my system.
For working with samples, I haven't tested either of those but I've heard good things about 1010 Music's BitBox and the Morphagene by Make Noise, 2 very different takes on sampling. Again, it all depends on what you would like to go for, just throwing you a few more ideas to look at while waiting for more experienced posters.
Hope this helps anyway ;)
D.

--- Voltage control all the things ---