Have your tried the "MIRx Mode" in MIR? That will give you preconfigured reverb, eq, etc... for every instrument.
IMO MIR Pro and Vienna Suite are very powerful tools, but they maybe a bit of overkill for someone that is just getting started and is working only with VSL libraries. I'd recommend you spend some time just with MIRx mode and ignore Vienna Suite for now, to see if you can get the sound you are happy with.
When it comes to buying new sample libaries, I only purchase new ones once I realize I've outgrown the library I'm using. For example, I was using the SE orchestral strings a lot and eventually needed more articulations and samples so that is when I upgraded to the full version. My philosophy of only buying hardware and software once I've outgrown what I currently have, and know exactly what additional features I need and will use, has saved me a considerable amount of money over the years.
Also, if you are thinking about buying more VSL products, check out this months deal on Vienna Vouchers.
All the best,
Michael