Roman Cavalry questions

[Aulus Perrinius]

I was wondering since the roman cavalry had spears would they have used them like Napoleonic Lancers? Is there any other cavalry from that time/era that would have done so?

Also, how effective were the Contarii? and what did Josephus mean when he said they had helms and cuirasses of the infantry pattern?

And finally can anyone tell me anything about how they would have fought from horseback (besides the obvious I mean :lol: )

-Thanks