Coat: In order to grow and maintain a nice Setter coat you will need to be proactive with coat care. Irish Setters can take 2-4 years to grow in to their full genetic potential. You'll see the feathers on the back of their legs coming in first, most will already have leg feathers started when they come home at 10 weeks. Around 4-6 months the skirt and tail feathers will start coming in. To continue growth you should get yourself and your puppy in the habit of brushing at least every other day, when brushed frequently the sessions should only take 5-10 minutes. 
Baths are suggested about once per month or as needed for pets, to keep the coat in show condition you should bathe with a high quality shampoo 2-4 times per month.
Males will need their 'pee feathers' cleaned daily to prevent hair breakage (this is really only necessary for show Dogs but of course contributes to the overal beauty of all Dogs). This can easily be done by keeping a spray bottle of water (with just a little leave in conditioner diluted in it) and spraying the skirt area just in front of and around the sheath opening once or twice per day.

Nails: Setter nails tend to grow quickly so I suggest trimming them once per week. I trim the puppies nails once per week starting at 10 days of age, the more you work with your puppy the better they will be for their nail sessions. A nail grinder is a useful tool to smooth out the nail edges after a trim or can even be used in place of clippers as long as the nail has not been allowed to grow out very long.

Trimming and other hair removal...
*If you are unfamiliar or uncomfortable using shears or clippers on your dog I would suggest paying a professional to teach you*
Paws: Hair removal from the pads will help them keep traction on slick floors such as hardwood and linolium. First shave the hair from the bottom of the paw using a #10 blade, use quality pet shears to trim the hair that is missed by the clippers. Some people really lake the hair that grows between the toes, trimming this hair is personal preference but if you choose to leave it make sure to check it for tangles or burrs/foxtails during you regular brushing. If you choose to trim it brush the hair up from between the toes and then use quality trimming shears to cut the hair. Blending shears can be used to blend any trim lines and make the trim look more natural.
Undercoat: Excessive undecoat can be removed from the back, sides, and upper arm/thighs by using an Andis de-shedding took and carding comb.
Ear and Neck: Show dogs should have this trimming done using a #10 blade 7-10 days before a show to allow it time to grow in properly for the show and then touched up the day of. Pet dogs can use a slightly longer blade such as a #7 or #8 since precision isn't as important. The top 3rd of the ear leather is shaved against the grain and blending shears are use to soften the hairline where the ear meats the skull. It is important that you do not pull on the ear as you shave as this will cause the shave line to go past the ear leather onto the skull. The Neck gets shaved from about 2" above the breast bone up to the jaw as shown in the image below (image pending), use the blending shears to blend the lines on the side of the neck and jawline.
Show dogs should have their whiskers trimmed off the day of the show and their 'ducktails' trimmed down with blending shears.

Recommended grooming tools:
Images pending