Well you're not really supposed to ask this in this forum, you're supposed to have a mod to post..... but oh well.
1) download the hacked Civ3editor from the utility programs forum. using the add button on the appropriate tab you can add a tech.
2) make out 100x100 pcx files, put them in .....civ3/art/wondersplash. then go to .....civ3/texts/pedialicons.txt and go to the bottom and add the pics to that, the first building you create is #74. if you skip a space, you have to skip that number too, plutarck has a whole thing on this in the guides forum.
3) same as #1
4) same question as #3 I suspect, I don't see difference other than the wording.
5) simply open up Civ3Editor (preferably the hacked one) and change the governments in the governments tab.... edit rules.