Solid 1.8m, chain link 2.75m

maybe late but if you r still interested. removing the staircase is not possible as it eliminate running distance for the floor. If you break the firewall wall from the adjacent unit for access it violates the firewall rule. Unless you merge all four units into one single title and reapply then can be done. Then again in Malaysia anything can be done for the right price.

depending how old is your building. usually submitted to local majlis but their filing is haphazard and I seriously doubt you can find. If building by a developer your best bet is to go to their c&s consultant if cannot find developer. Might need to pay a small fee for plans. If you know the contractor you might get the full set of plans inc the electrical and plumbing. if you are doing renovation, the architect can roughly sketch the plan for you. no need for original.