you can apply textures and they will show up in renders

depends on the type of particle you're using
if it doesn't have (s/w) next to it it wont show up in hardware render, but if it doesn't then it wont show up in software render

they all show up in mental ray (why you'd use the other two is beyond me)

to apply a texture switch the particle render type to blobby, right click and assign a new material and do it like normal

alternatively you could just use instancing to make your particles look like a model you made