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...If BU get 95%, is it when It will get activated and If yes, we will have to download another client or they will take control over the current Bitcoin Core Repository because It looks pretty much confusing... and should we switch our coins somewhere else after that?
To answer the OP,
(1) My understanding is that BU has the coded ability to hardfork at 51%,
but it is likely they will wait till more, around 75% consensus according to what I have
read previously (75% = current verbal agreement.). As a comparison, SegWit has
it's consensus set for 95%.
(2) If BU hardforks whether at 51% all the way up to 100%, and you wish to follow their
chain, whether it becomes the main chain or is one of two, you will need to download
their BU client in order to transact on that chain.
(3) If BU hardforks, whatever the result, Core Github and BU Github will remain separate
most likely. If in the event Core devs would like to work on BU later, they will need to
participate on the BU Github, presumably.
(4) If the hardfork occurs, your coins will be safe as long as you do not transact until it has
been shown to be safe. You will have the same amount of coins on both chains, both
associated with your single privatekey. It is best for noobs to wait and hold their coins until
the community and devs determine it is safe to move and how to move if there are any
special precautions.