There are a long list of companies which have held or hold Bitcoin in their balance sheet or have accepted it as a means of payment for the goods or services they offer; So Telsa announcing a Bitcoin purchase would surely create some traffic, but would not massively affect the price as you suggest.
Bull run can soon come op just be patient but I am only not sure if btc can instantly go to 100k after that as I think the price is still high and there are still ath's that we need to surpass (e.g 70-80k) before we ended up on the value you are assuming but to your other 3 questions, my response is the following; 1.) Realistic if what they are predicting is also realistic amounts. 2.) A major buying event 3.) Depends on the quantity. The larger the btc they buy the greater the impact.