Covering Patio And Wall Hacking

All,

I just bought a small condo and because this unit is kind of 'special' I want to see if I can extend the walls of my condo to cover a small part of my patio and also hack down a wall to include new windows.

As such - can anyone advise

1. Who's approvals I need ?

- Building Management?

- URA ?

- BCA ?

2. I don't plan to hire an interior designer - so who do I hire to do the drawings and apply for submission? I only plan to hire a contractor later to do the actual renovations

- Builder?

- Architect ?

- Contractor?

Thanks!