things you don't need:
output module - mono straight from the vca is fine for starters
buffered mult - you do not have enough v/oct destinations to warrant this at this point - if you want a mult get a passive or some heeadphone splitters or stackcables
adsr - pams will give you an envelope generator (or 8) and rings doesn't need one
things I would swap:
nRings - for Rings - get the full size one it won't be that much more and it will be much more fun to play with
pico dsp for fx aid xl - yeah it's more expensive and takes up more space - but it has more algorithms (32 swappable), more modulatable and is stereo in and out (unlike the pico dsp) so if in the future you get to a point where you want to effect a stereo signal then you can
Maths - brilliant buy it - download the illustrated manual and work your way through it a few times
I'd also be tempted to go for a simpler (and cheaper) sequencer to start with maybe the pico seq (the one that has 16 steps and memory slots and quantization) - possibly or a beatstep pro - multiple sequencers can be really handy - so a simple sequencer to get you going and then dive into something more complex such as a rene in the future
the next modules I would buy would be kinks and shades
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities