A good place to start with opaque water colors is to paint a gray scale .
Gives you a good feel of working with the mixing and just needs a brush and two colors .
For the gear, you need to set a budget and and base it on that.
As Bones says any old thing can get you started .
I dislike immensely if bristles fall out, yet was surprised when viewing a Monet that there were several brush bristles stuck in the paint.
I once found a dead bird that hat been flattened and road mummified
glued it to a canvas then glued dried leaves on the canvas and panted over it with cheap acrylic house paint .It was fun to see folks discover the bird in that ...so yesiree, anything goes.