Hi Nashtyboi,
Welcome to ModularGrid :-)
Consider the 1U - Audio I/O module from Intellijel, that provides you proper audio input and output possibilities, then you don't have any worries there. The output you can then take to your mixer or directly to your audio interface (to DAW). If you want to use monitors/speakers (and not only headphones) then take a (small) mixer, you can then take the main output of your mixer to your monitors and one of the sub-outputs to the DAW.
For building a new rack (assuming you have no external synth gear already) please keep in mind a minimum classic setup of something like this: 2 VCOs, optional a ring mod, 2 filters, 2 EGs, 2 VCAs (1 lin + 1 exp) and don't forget to add at least one better two LFOs. For more details you also can have a look at a post between Metal_Serra and myself in the post called "First modular rack build" also here in "Racks"-forum where I go into more details, this is for most of the parts applicable here too :-)
Good luck with the planning and kind regards, Garfield Modular.
For review reports of Eurorack modules, please refer to https://garfieldmodular.net/ for PDF formatted downloads