Fitting a new hood

Hi everyone, my first time posting a thread on here so any help would be very much appreciated.

I am in the process of installing a new kitchen which has took the best part of 4 months due to many many difficulties (my lack of diy skills being the main one). Am at the final stages now and need to fit a hood for the electric ceramic hob.

1) How high does it need to be from the hob?

2)The hob is in two parts, the actual chimney bit which is rectangle in shape and the triangle bit which sits lower and has the vents. My question is with the rectangle bit. It is metal but only has 3 sides so is quite flimsy and bendy when cutting it to the desired length (which I need to do as it is far too long). Any ideas on methods or tools needed to cut the chimney bit of the hood to length?

Sorry about the length of this but am desperate to get my kitchen fitted. There are only so many things you can cook with a microwave!!

Many thanks

The installation book supplied with the cooker hood will give you the height of the the hood above the ceramic hob. It is important that you get this right. Is the width of the hood correct for the size of hob?
As to cutting the venting, no idea, can't help you with that.

Put it higher than the cook is tall. Otherwise they will keep banging their head on it.

If you put it higher than the cook then if may not extract the fumes, stick with the recommend height in the book.