No cons to water cooling apart from the price. Never fear of a leak, that's not going to happen unless you yank on the tubes with a considerable amount of force or cut the tubes. It's even easier to install than air cooling heatsinks.
That is a great buy for the monitor
For the keyboard I would recommend a Ducky one
http://www.pccasegear.com/index.php?...1361&vk_sort=4
About $140 AUD and comes in a ton of colours. It's expensive because of the mechanical keys, but if you don't really care about them and just want the LED back lights, the best option is this Razer
http://www.pccasegear.com/index.php?...ducts_id=22074
But you can only get it in green.
For the mouse, it depends on what you want. Corsair have a great FPS mouse with a sensitivity button (deigned for good sniping). They also have an MMO mouse which could come in handy with Total War if you configure the custom keys properly (quickly giving orders to your legion with a single click), but the key placement is a little strange in my opinion, but you might like it.
http://www.pccasegear.com/index.php?...h=258_697_1303
Logitech have a great MMO mouse too which have a bunch of key on the side where your thumb is (which light up any way you want, so it can match your board colouring

), I think it's got a great appearance and it has a nice braided cord. Definitely worth your money.
http://www.pccasegear.com/index.php?...ducts_id=21066
I know these seem fairly pricy, but they will last a long time
