Starlifter, you've said that you play for a spotless reputation (actually I generally do too)--so how do you "get the AI to do research for you" as you say?
I make embassies, or better yet, get Marco Polo... then I study who has what, and keep a general feel of when everyone is finishing their research so I know about how long it will be till they are done. Before they can finish a piece of research, like say Feudalism, I will trade someone for it (or finish it myself), then gift them. That way, their research is not "wasted" on an advance that the world already has paid for.
Do this for all 6 civs at Deity, and science will go very fast. At lower levels, I have just found (playing Warlord in this GOTM) that they research so slow (even at King they go very slow) that after the first few advances, they can never catch up, and by gifting them, their science cost is so great that often the game is over before they finish another advace (at lower leves). At Deity, their science rate will be adjusted to keep producing advances (the AI "cheat").
Any tips about better diplomacy, or manipulating diplomacy?
Make alliances early in the game when you are weak, and keep them. Gift science & swap maps, too. They often want something to keep allied, but I always gift them scinece anyway. Ad long as they are not too hostile, you can get gold from them (25 to 400 per contact) after you "give in" to their demands for your science.
If you keep lots of gold, they're gunna want gold, which I don't like to cough up. Spend your gold (barbs will ransom your cities dirt cheap, too), and that will make your allies feel sorry for you bank account and gift YOU gold, after you "give in" for an advance!
At low levels, the AI is worthless once past the very early game trades. The Sioux (my ally) in my GOTM 8 have not had an advance in 3,000 years, and I've given them EVERYTHING, including Stealth, LOL.