Effectiveness is influenced by capacity of unit. If you are trying to mount a 270 cfm fan more than 30" above cooktop, then it may make noise but will do little to clear the air. If it is 1000 cfm, then it can be higher than 30". So the answer is "it depends". Most people don't mount them more than 36" above the cooktop unless it is a really high powered unit.

If you will like to go little different than Indian / traditional one, mint green colour is in trend and goes well with brick colour walls. Looks good if you have white appliances, crockery and some other elements that are visible with it. (Sourced from google images) https://goo.gl/images/Wyu1kR

Manpreet, Congratulations on your new home! You can go with BWP ply with laminates. You are right in your choice of matt and glossy laminates for base and wall cabinets respectively. Without knowing your tastes, I am taking a chance to suggest you 14541 for base and 21187 MR+ from merino catalog. It looks good. Thanks, Nitin CORNERSTONE DESIGNS Bangalore.

Grey is trending big time now. And don't worry about it being too dark. You can offset that with a white counter top, white dado and steel accessories and of course interesting lights