You should review the Condo Association Rules and incorporate any restrictions into your design. The walls you intend to remove should be "non-load bearing". Most condo's share the plumbing stacks for waste. If your design includes moving a toilet to an entirely new location that is not a "shared" location with the other units, you may have an issue. I am not sure what sort of revisions you want to make to the heating and cooling system, but if it involves work on the roof or on an exterior wall, you may have an issue. As an Architect, I can help you try to coordinate your wants and needs into a plan that works within the rules of the Association. Feel free to contact me. Good Luck!
Naaman G. Landers III