PMT preamplifier help needed

Hi guys, I'm stuck here trying to understand what I actually need to build to read out & amplify 5ns pulses from the Hamamatsu PMT (**broken link removed** if this is of any help). So my knowledge of analog electronics is low, but my boss insists I take care of this. So the problem is (by vague description of my boss): 100MHz pulses (~200uA peak) coming out from the PMT and need to be voltage converted and further amplified. He stated I need 2 stages: gain=1 transimpedance amplifier as a current-voltage converter (for which I have to calculate feedback resistor and capacitor values) and then amplifying op-amp stage that would bring the signal to ~1V level. So I have here **broken link removed** in hands. If the gain stage seems pretty much straight-forward, I absolutely don't know where to start from in choosing feedback resistor and particularly the capacitor. The questions are: why do I need 2 stages, if i can convert and amplify in once. How to pick a feedback capacitor value as well as why do we need one there. Any kind of hint/advice would be very appreciated!
Thanks!

As a starting point, you may read here
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What's All This Transimpedance Amplifier Stuff, Anyhow? (Part 1)

Also there are some info if you read the ADA4817 datasheet.