personally, i think you can get almost as good a sound from your fingertips as from the fingernails. my wife hates when my nails are even a tiny bit long and so i keep them relatively short. you learn to adapt. as for picks, when i fixed my soprano 12 years ago, i bought a couple felt picks. never really used them, but remembered using them when ukulele was first introduced to me in like the 3rd grade. there was a kid recently in a local ukulele club i go to who is starting out and loves to use a regular guitar pick and it made his instrument sound aweful (plus he was a little out of tune and didn't seem to care and the guitar pick really made that stand out). he insisted he liked playing with a pick better, so a couple weeks ago, i gave him one of my felt pics. because it's quite a bit softer, it gives a tone closer to your fingers. his sound improved dramastically.
lesson: if you're going to use a pick, please use a felt pick!