Typically a Trust is governed by the Trust Agreement. You need to look at the specific wording for the “Trustee’s powers”. I’ve seen Trusts that require a majority and others where all decisions must be unanimous. You may want to contact the attorney who originally prepared the Trust Agreement.
That depends on how the trust is worded. At times they must agree per the language of the trust and other times it does not have to be a unanimous. I would suggest Consulting with a qualified attorney to review your documents so that he or she could advise you and exactly what your document requires.
It first depends on the terms of the trust. The document may speak to the rules when it comes to multiple Trustees. If not, your state trust law will govern. In most states the default rule is majority rules if no consensus can be reached. If Trustees are deadlocked any Trustee can file an action in court and ask a judge to make a decision based on what would be good for the trust as a whole.