jump on the windows when the lights are not on. if you touch a light you will be zapped and fall down. climb to the top of the building and cut the bars using your laser pen.
The friendly spy is being humorous on the roof of the building : you don't make your legs stronger, you get the special bowtie from second spy. When you free him from the house on Toupee Terrace (where the lights zap you), he gives you the Grapple Bowtie that lets you climb, and go from roof to roof. (see related question)
There is no greenhouse on Spy Island.
Go around them to the left. Go past the guarded building to the red building farther left. Climb to the TV tower, and then grapple back right to the antenna on the tall building's roof (a friendly spy suggests this).
on the roof
Once you have the Chameleon Suit, you can free the first spy at the docks. Put on the suit, climb to the roof, then head left until you reach the door. You will have to avoid getting hit by remaining still when the guards are near. (see related question)
JUMP!
You jump
He's inside a bared roof, but you need the laser pen you get from the 1st spy you save in the docks.
There is a large hole in its ceiling. Climb up and enter.
roof top
You cannot enter the building. The second kidnapped spy is in the attic, and you can climb to the roof by jumping from window to window when the power goes off for each one. You will need the Laser Pen from the first kidnapped spy (at the Docks) to cut the bars.
the second spy is on top of the roof in that little house thing and you go in with your camo suit.