I am going to make a rectangular port, does it make any difference if I make it in the corner (as opposed to make the height of the port the same as the height of the box, which is what i commonly see)?
Because if i make the port height the same as the box, then it'll be too thin, i would rather have a better ratio between port height and width.

 

why would you have to make it the full height of the box??? I mean if your box is 15 inches high, you can make the port like 10 or 12...It would be somewhat harder to construct but would work just fine. but you are right, you dont want it to be overly thin. if you go to the jlaudio website, they have a few very good box building articles that you can read with all sorts of different setups, pictures, and diagrams.

you could probably get some more exact answers there.

 

I would suggest posting a drawing of what you are talking about...

 

Corner vents aren't uncommon, and should work fine if the size is right. I think PVC or ABS pipe is the more common approach. (Which you can have an elbow bend if you need more length than will fit in the box). I would follow the speaker manufacturer's instructions as to port size and length.