One definition of an improvement is that it extends the useful life of the property or one of its subsystems. Replacing the air conditioner extends the life of the HVAC system, and reworking the French drain and foundation waterproofing extends the life of the foundation. I would consider those both to be improvements and I would not think that you should split the interior and exterior waterproofing since they are both part of improving the foundation. Because the deck work was targeted to specific areas, I would consider that more along the lines of a repair.
If you are traveling to maintain your rental property and to supervise work being done, I would not think you would have to capitalize and depreciate your mileage as part of the cost of an improvement. I think any travel you do to maintain your property is an expense.
