Will I lose much by buying a spray gun not suitable for water-based materials?
You never got an answer so I will give you a simple one. I'm not a painter and just have a small amount of general knowledge...


  And since I'm a total newbie in painting, I've decided to ask a couple
  of questions here:
  
  
  What are pros and cons of water-based vs solvent-based paints?
  Will I lose much by having a spray gun not suitable for water-based materials?
  


Pros and cons of water-based vs solvent-based? Well a simple answer would be that water-based is easier to work with, easier to clean up, better for the environment, and healthier. Solvent-based is tougher to work with and clean up, not so good for the environment, but generally considered better and more durable. Often most professional or factory finishes are solvent-based.