I doubt very strongly that Dr Rees built the wharf (it was built in 1837) so that it could be used as an emigrant receiving area for those who arrived in Toronto by ship - though it may well have been used for this - as far as I know all emigrants to British North America were given a health inspection on arrival in the country, in most cases this was at Grosse Isle in Quebec. I have certainly never seen any mention that Dr Rees himself inspected immigrants and even if his wharf was the designated passenger wharf for some years it was almost certainly used for many kinds of 'cargo'.
There is an 1857 map of Toronto that shows Rees' Wharf at
http://www.toronto.ca/archives/images/zoom_s0088_it0013.htm
If you want information on what is being built on Bremner Blvd between York and Simcoe I suggest you look at the Southcore and 18 York threads. One assumes there will be two additional street numbers on Bremner but sometimes when a building has multiple sections and entrances (e.g. offices and residences) it is assigned two numbers to avoid confusion. As the site it is on the north side of Bremner these will presumably be even numbers.
In Anderson's Toronto City Directory for 1868/69 Dr Rees is listed as:
Rees, Wm., M.D., h Simcoe bet Front and Esplanade.
Rees' Wharf, Esplanade at foot of York.
His neighbours on that stretch of Simcoe were railway car cleaners and labourers which supports the view that he was really quite poor at the end of this life and shows why he kept on trying to get compensation from the government.
The 1862 City map at
http://www.toronto.ca/archives/map_atlases.htm also shows Rees' Wharf and Simcoe Street The Goads Fire Plan of 1880 (on Toronto Archives site) shows that the area was then pretty much all railways except for the Marlboro' House Hotel and a school - certainly no sign of Dr Rees' home left (he died in 1874).
Rees had a long-running fight to get compensation for an 'occupational injury' - he was hit by one of the lunatics in his charge - and in his 1865 "Memorial" to the Governor he notes the many things he did, including
"8.—The erection, at his individual expense, of Public Baths, a Commercial Dock, and Pier in the City of Toronto, 1837." The full statement is at
http://www.archive.org/details/cihm_47519
Thanks to your question I have also found a recent article on Rees, you probably know of it already but if not it is: "A solider in the service of his country": Dr. William Rees, Professional Identity, and the Toronto Temporary Asylum, 1819-1874. by Danielle Terbenche.
Histoire sociale/Social history, Volume 43, Number 85, Mai-May 2010, pp. 97-129 It is only available online to subscribers.