Hi Christina,
What a coincidence! The Beresford is well located, close to the main bus station and the Liffey and it's totally safe to walk around at night.
For animals in Dublin, I would suggest Phoenix Park with its deer population. Otherwise, you could reach the coast
with the DART train in 30 min and see seals in Howth Harbour if you are lucky. You may also be interested in
these options for a half-day trip , if you can spare the time of course.
As for getting to Kildare, the fastest way would indeed be a taxi (more info on getting one can be found
here, but you could ask the Beresford Hotel to book one for you). Busses would take at least 2H30, which isn't ideal before catching a flight. I can see that the company
Wild Rover Tours offers a day tour that includes a sheep dog demonstration. Is your flight late at night and could you spend the day on a tour?
Let us know how it goes :)
Antoine