Question 1: Do you feel that granting creatures advantage if they attack from high ground is to powerfull?
Yes - BG3 as it currently exists makes it too easy to get advantage. That is an incredibly strong bonus, and shouldn't be so easy to get.
Question 2: Would you prefer if the advantage gets replaced with a flat bonus to hit?
Yes; I like encouraging high ground, but advantage is too much.
Question 3: Do you feel that the disadvantage penalty for attacking someone on high ground needs to be removed?
Yes - disadvantage is a major penalty; giving the attacker a flat penatly to hit, or the defender a bonus to AC, would be better.
Question 4: Would you be ok with high ground granting cover to people in place of it granting the attacker disadvantage?
Yes - this also opens up feats like Spell Sniper and Sharp Shooter to be added to the game, as they would allow someone that invests in those feats the ability to ignore the cover bonus.
Question 5: Would you prefer if the bonus and penalties for high ground get removed alltogether?
No - I like the tactics it currently encourages.
Question 6: Would you prefer the heigh ground 'issue' be resolved in a different manner? If yes, please explain in your post how you would like to see it solved.
No - a flat bonus seems easiest and most balanced.