Is the marriage contract considered valid if the bride's paternal uncle is her proxy without her direct knowledge of his wish, and is the contract valid if the bride feels hesitant and afraid during its completion due to a side issue?

If your paternal uncle is among those authorized to contract marriages (wali), and there is no one else with a stronger claim than you, or if there is someone with a stronger claim but he has customarily authorized you to arrange the marriage, then the contract is valid. Your intention to postpone the contract does not affect its validity, and the dispute that occurred during the marriage contracting session does not invalidate it.