I feel the polyphonic discussion is a little misguided, Modular synths are monophonic, if you want a polyphonic synth I use other instruments for that which are polyphonic. What is so spectacular about a modular synth are the harmonically rich and sometimes larger than life soundscapes you can obtain with a well constructed modular voice. Those types of sounds are not well suited to use in chords, you will simply need to strip down those sounds and make them more narrow, so now the whole polyphonic idea looks quite a bit different.
Think of a modular as a string quartet where you have different voices, each with its own distinct signal path and each playing a different role in your composition.
The 4ms 6 oscillator wave table module is an impressive piece of gear, it's pretty and it comes with a nice software that allows you to edit and morph between wave tables. For the price of it you could buy 4 different oscillators, take each of them through different signal paths and come out with a more rich orchestral overall picture, each voice obtaining clarity and definition, Check out Doepher, Dreadbox and other companys that make quality modules, the Behringer Neutron mentioned above is a very good semimodular synth, there you already have two voices and you can patch in and out of it in many different ways, for a wavetable synth check out Waldorf, I think you can get 3 of them for the price of the 4ms module. But you need to do your homework, nobody can tell you what to buy. Pretty much all the modules on Modulargrid are presented on youtube and going through that material is highly educational.
You need filters and/or low pass gates, a blend of the two is good, you need envelopes, you need vca's, a mixer that takes both cv and audio signals and with an output which is audio level, effects. Maths is good in that it has different functions, it's a slew limiter, a mixer and an attenuator. It can do a number of things, again a semimodular like the Neutron, although it is more of a east cost synth while Maths is a take on an old Buchla module, will serve you better in the beginning. But you need to study, there is a ton of material out there. Final word, if you want 4 or even 6 voices that sound the same, get yourself a nice polyphonic synth, a modular is a wall of often very distinct and different sounding signal paths.