I fully agree with: The speed at which the game progresses is too fast, expansion-wise. I find it hard to have enough time to define myself in any way. What I mean is each era feels way too fast. I want to feel immersed in the bronze age, I want to experience the medieval, etc. The other things you mention I can not so much view as a problem or annoying. But you certainly have a point there, that each eara should be longer, anyway for being able to gather fame stars. Switching cultures? Not a problem, in my taste. If you want to play industry-heavy, simply choose the next culture that is also industry-strong, for example.

Even when I play at the slowest speed, it's too fast.

I reach "contemporary" era, when in fact, my technology is medieval.

It need more "star" to get to change era.

Also, tech cost should be more costly when you reach later eras.

In a slow game speed, I build many science, the last big techs was only 3 turns.

In the last eras of the game, I feel like I never play with all what the game give (tanks, planes, etc).

When I reach this point, I just will win the game in another way. Or it need more techs also in the last eras.

For sure ultimate techs are too cheap. Anyway, the game say me there is just 100 more turns and it's over.

I would like to set or remove this turns limit.

So everyone knows the navy in this game is almost utterly useless.  More water helps, but largely you could play the game and ignore navy completely and lose nothing for it.  This is crazy, navy is so important in actual human history, so what makes navy useless in this game?  As many have pointed out navy ships should be able to do things to costal areas, but that is hardly a fix.  The problem is there just doesn't have to be a lot of costal infrastructure.

The problem is troop movement.  If you could pair land troops with naval vessels and gain their movement and navigation, than you could effectively use navy to drop units behind enemy lines.  This would create a situation where you would need to build navy to defend against navy and then people would actually be forced to take it seriously, lest you have a massive army dumped directly on an undefended city or capitol.

Oh and navy movement is way too low.  The southern cap of africa was a shipping lane because for most of human history it was faster to move over water even if you were going way farther, than it was to go shorter over land.  Not so in human kind, in fact there is almost never an instance where the sea routes are faster.  This should be fixed.

So in conclusion.  Fix navy, it's an embarrassment to this game.  Fix it by giving naval units more movement and letting them transport troops.

I agree with you to an extent but I think things like this should be optionals. Similar to the way Stellaris (made by Paradox) does things. Rather than makign thigns fixed it makes things an option.

So maybe before game start you have the "Option" to "Restrict Cultures Based on Behaviour and Civics".

With regards to timing I think you're right though I'm only on my first game at the easiest difficulty but I'm already Contemporary at 1345 CE.

And I've been purposefully slow at upgrading my eras!

But to take another leaf from Paradox - make these things optional. If you play one of their games they have a TON of modifiers pre-game that can slow or speed up the development of your civilisation/empire. Such as pop growth, district (planet) count, etc.

Seriously I'm not a shill. Just check out my Steam Profile. Besides Paradox and Amplitude play to different audiences. Paradox is realtime. Amplitude is turn-based. 

I just think Amplitude could learn a lot from Paradox in its use of options, features, etc.

Don't use Civ as your base. Use one of Paradoxes games as your base.