Hi,
I just did my landing so I thought I'd share the info for people who are doing it by bus.
I took the Go transit from Union to Niagara Falls. This requires that you take lakeshore west Go train, transfer at Burlington to take the 12-Niagara Falls Go Bus. There were taxis parked outside, because of the weather I took one to rainbow bridge, he dropped me off right in front it was about 10.00 for the drive. I then walked over on the pedestrian side, to cross the bridge you have to pay 50 cents. Once I got to the US side, I told them I'm doing a flagpole landing, they handed me a sheet and I headed back on over to the Canadian side of the bridge and presented my passport and the sheet. I was then directed to a building nearby and they did my landing I had to provide something with my address on it so I gave them a bank statement.
You do not need a valid US visa to do this.
Good luck!