Sorry for not being able to give specific answers, but I have an advice. Always look at reviews about products. 95% of the time they will be correct about the product.
Edit: Sorry, forgot - could you show me what a pre-war apartment means? :) Thanks.
Not knowing which city or country your apartment is in, or what floor your apartment may be on limits some possible answers. In general if you wish to maintain the "architecture" you should chose the least obtrusive system. As far a contractors it will be, should be, a slow and careful process. Seek recommendations, view their previous work, verify licenses etc.
Thank you all for your answers. I stay in Morristown and I found out about a company called All Week Air Conditioning
in Morris County, NJ who are specialists in old building air
conditioning works. My neighbours recommended me this company and I also
found them on Angie's list. Anyone has any experience with this
company? Should I hire them?
Make sure you have sufficient electricity output available. If the contractor says he has to rewire something, be sure he gets a permit and that the wiring is inspected and approved.
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