During working on an iOS app I'm getting some confusions and want to ask community that how should I handle those.

i) Is that necessary / standard to have all icons within a particular width or height. For example these 3 icons I'm using right now here https://www.dropbox.com/s/irzmg89h3b6bt6i/temp01.png?dl=0 have three different dimensions. 22X19 (heat) 17X17 (pencil) 20X20 (arrow). Should I make them consistent as of width or height? Where should I read more about that?

ii) Also in above given example. I'm using three different colors for three different icons. Orage(heart), green(arrow), home(gray). In all three, only heart is clickable. Will user get confused what is clickable and what's not?