Watch the Tuners, Straps, & Stuff online guitar lesson by Marcy Marxer from Ukulele for Guitar Players
You don’t need anything but a uke and this course to play the uke. TrueFire has a tuner and a looping device built into their site. You may need a strap if you’re playing standing up.
Picks are optional, of course. Most uke players don’t use them. Felt picks and more standard plastic picks have been used since the 1920’s so if you like to play with a pick go right ahead.