I am researching tech way too quickly to enjoy the game fully. A way to Era lock or adjust the cost of technology is a must!

I agree, but it's only too quick when you are big. There needs to be some kind of scaling because in my last game (3rd from hardest) I was on the moon before the AI got steam power... all because I rushed the 2 AIS near me on my continent, so had nearly the whole thing to myself, then got to the New World first. All the land = more pop = more scientists... clearly that is not how the world works, or India and China would have tech 500 years ahead of what we have today. Science needs to scale to population, and be slower overall.  

"all because I rushed the 2 AIS near me on my continent "

Well, you managed to put yourself in a good spot, how would you be astonished from that ?

For me it feels like researching one tech gives too many new things at once. From one tech, you may get a new unit, new building, a new civic, and maybe more. That could be easily split up, so that you only get one or two things from a tech, adding 30 or 40 more techs to research. 

I don’t feel that it is too high in general. Especially since there is an era block. My first game I started in classic with the Zhou due to lots of mountains in my area. I got so much science! But when all the techs of classic were researched, no more research was possible until next era. Science points? Lost. The game ended due to max turns. I started no wars and perhaps I just missed some opportunities to expand even without war… The point is that in the end my empire was not that big. All in all I think this is not a question of too much science but of difficulty balancing. On low difficulty it is easy to expand greatly and therefore achieving high science score. On high difficulty it should simply be hardly possible to expand that much. 

I think eras should last a little bit more. Maybe make all science a little more expensive. Also, more stars to advance. Not 7 stars, maybe 15 stars are needed to advance.

While I'm not sure I would like to make science more expensive, I do sure don't want to change the number of stars. 

1. I see no one going up with 7, so it is not an issue. 
2. I like having the choice.
3. I fear some players might get a bit stuck (what if you get easily 3 scientific stars but won't fight, can't expand, possess to few cities to grab a lot of agrarian, influence, money and builder stars? Would you just waste your research which is the only thing going for you?)