Working cocker as a first time dog owner here. We failed miserably to train him to walk on a loose lead, not a mistake we'd make again. But he's mostly off lead anyway, with good recall, and largely uninterested in other dogs so it's not a huge problem.
Be prepared for lots of adoration from other dog owners/random people. So many other dogs are cross breeds now that a pure bred seems to attract a lot of attention - or maybe it's just that ours is spectacularly beautiful!
Yes to regular grooming. We have never had him clipped other than his legs for surgery. He had elbow dysplasia which is very common in cockers, and very expensive to fix, so get good insurance. But that meant his leg fur went fluffy, while the rest of him is still quite sleek.
He loves the beach above all things, but any muddy puddle will do, so always have a towel/drying coat or whatever on hand, and say goodbye to clean floors. And say hello to being permanently covered in dog hair...
People say they're crazy dogs but he's really not. He gets about 1.5 hours exercise a day which seems enough for him, and he's happy as long as he is with his people.
The puppy stage was really not too bad, other than chewing, which he's now outgrown. Some cockers resource-guard but we taught him to swap for treats, and that has never been an issue - in fact his favourite game is to steal slippers/socks/tissues and stand with them in his mouth with a soppy spaniel grin until we swap for a biscuit. He has us well trained!
Can you tell we love him, and cannot imagine life without him?