Save your $$$...the only patching thing that will wreck a modular is patching outputs to outputs, as the output stages of a lot of modules aren't diode-protected against reverse voltages. Otherwise, the whole point is to patch everything to everything else while avoiding that one critical misstep, which one typically sees when people confuse multiples with mixers (which they aren't!). The far more important things to remember have to do with POWER...connecting the busboards properly, making sure where modules want the "red stripe" on ribbons, etc. Just proceed VERY carefully if you have to mess with any of that, and you'll be fine.
As for utilities and the like, just slap up a build of the current system and link it to a forum thread. You'll have plenty of experienced people poking at it for $zilch, and while you might get several answers...look at 'em as several IDEAS, implement the one(s) you like, but make sure to keep the other suggestions in the back of your mind in case you need 'em later. The MG Forum is also a super-useful place to get patching tips, etc. So, save the money for...well, more modules, but you'll see how THAT happens once you start using what you've got!