1- In qunoot in prayer, am I allowed to do it in any language since its not obligatory part of prayer?
2- How far should one raise once hands for takbeer at the start and end of prayer? I have seen some people raise it just slightly, some to their chests and others all the way to their shoulders.
3- During prayer some people will raise their hands every time allah akbar is recited whilst others will only raise theirs hands at the start and at the end. Is both permissable?

1- Yes.
2- It is recommended to raise the hands so that the thumbs are next to the ears.
3- It is also recommended to do so.