1. Yes, treat for a UTI, no pyuria does not rule out a significant infection, although disagreement on this point exists.
2. No, he is not in sepsis yet.
3. He is in a negative fluid balance, remember to count insensible loss.
4. Now he is in sepsis. CHF unlikely since he is in a negative fluid balance, and findings fit the diagnosis of sepsis better. Blood Transfusion reaction possible, but symptoms started before the transfusion started