Question 1: What is the amount of damage increase if your forces are attacking from high ground?
Question 2: Do "2 high ground levels" give any benefit compared to '1 high ground level'? Sometimes your base is on the high ground and it exits onto the natural (that is actually on the 'neutral' level). The exit from the natural leads to 'low ground'. So comparing high ground to 'low-ground' you have double level of difference. Does this give any additional benefits?
Question 3: Does a Colossus receive a bonus when it is shooting from high-ground?