You don't need Guerilla Warfare to get partisans when your city is captured as far as I can remember.
I never research Amphibious Warfare by choice. Obviously, when the number of techs you are allowed is restricted and you are stuck wasting beakers on it then you can't do anything about it but get very annoyed

.
My favourite techs are: Bronze Working (I like to start the game with it), Trade, Philosophy, Astronomy, Theory of Gravity (anyone guess where we're going here?

), Invention, Electronics, Explosives, Industrialisation, Democracy, Economics and Fusion Power. Future Tech 93 is all right too. I started going in order of research but that fell by the wayside I'm afraid. I love Electricity actually, as it kills the stupid Great Library but I hate Flight for the same reason and try to avoid it as long as possible to preserve my beautiful harbour statue.
To jtb: This has recently been answered elsewhere but I'll repeat it for you anyway. Combat is based on random numbers generated by the computer which means that sometimes phalanx can beat battleships (although this is rarer in Civ 2 than 1 or 3

).
This link to Apolyton explains it all.
