what next and when? and what are these things on my glass?

[jess128]

I got my first fish yesterday, 2 perc. clownfish and they're doing really well. What should I add next? Like a cleaner shrimp or some kind of cleaner crew? And when should I add them?

I've also seen these little critters all over the glass of the tank. What are they? They're really small, like a millimeter each but there are hundreds of them crawling all over the glass. They're white in colour. Any ideas? Thanks!