When attached to your camera you will only be able to use the manual modes on the flashgun - it is not ETTL compatible so will not be able to communicate with the camera for automatically adjusting flash output.
That said it does have manual output down to 1/32 if that is what you are looking for.
Not with an EZ series - no They are for older Canon cameras.
You need to be looking at the 430 EX to be able to do that.
i mean does the speedlite adjust in the same way with its own controls? and also will it flash as normal when i pull the trigger? just you say it doesnt communicate with the camera.
Sorry, no, it does not adjust in the same way. Your only option is set one of the fixed power outputs from the flash which go
1:1 - 1:2 - 1:4 - 1:8 - 1:16 - 1:32 where 1:1 is full power and 1:32 is 1/32 of full power. To get the correct exposure you need to determine which of these outputs allows you closest to the aperture you require, then adjust the aperture to fine tune the exposure.
You might be better off looking for a used 550 EX as these normally go for about £90 to £120 or the 430 EX (Or EXII) for a bit more.