It's been a while since I played on warlord.

For the GOTM VI, can I expect to take a lead in the science or should I put my research to 0% as usual?

Do as you please.

But normaly you can expect a tech lead.

On Warlord, Large Map, 7 opponents, I think a player is better off doing research themselves. Odds are for a lot of open land before contact, and the AI techs very slowly on Warlord level. With a sparse map, AI tech trading is slow. With a sparse map, granaries are an interesting way to go to increase settler production.

If you choose the zero research route early, one idea is to build the Great Library. Then after Education is discovered and government is out of Despotism crank up the research slider and leave the AI in the dust.

Laro generally you can a tech lead up to monarch level by the late middle to early industrial age, warlord level a tech lead should be no prob, AI researches like a turtle.