There are lots of super guides based in Dublin City that you could get in contact with. Please take a look at the Tour Guides
directory for details and contact information.
The Maldron Hotel, Kevin Street is on the other side of the Liffey to the Q Park, Malborough St, you may wish to get a taxi from the hotel as it will take about 10-15 minutes by taxi. It is possible to take a bus, this will require a walk of about 5 minutes to the stop and about the same time the other end.
With regard to the Collision Damage Waiver, this is specific to each rental car company so please check their terms and conditions. We have some information on car rental
which has some great links to the Car Rental Council of Ireland should you wish to contact them too.
There is also another community post regarding car hire
that you may wish to take a look at.
Hope this helps, and let me know if you have any more questions!