Hey Funak,
first if all, thank you for your help!
I've just recently started playing VoxPopuli and have to say that it really feels a LOT more complete than vanilla.
Glad you liked it and I'm glad you found my ramblings useful.
One question I have is, if there are certain "benchmarks" which one should aim for in order to stay competitive or to get a rough idea about how good you are. I'm thinking about something in the line of "NC before turn 100" in vanilla.
And how do you when to focus on what. I simply tend to build all buildings, because they all seem to make sense and I start running out of things to build. But I'm pretty sure that's not an effective strategy...
There is not really an effective benchmark (as far as I know, but then again it is hard to grasp those things when you're just playing).
As far as strategy there are really four key-points that you need to keep in mind and which you kinda need to balance to not fall behind.
1. Growing your cities
This kinda feels like a no-brainer, I mean of course you grow your cities, but it's one of the absolute easiest ways to fall behind. The vanilla mind-set of 'this city will grow in 20 turns, it's fine' or 'This city is already 15 pop, no need to grow it more' just doesn't fly here. You're going to need to prioritize growth at points during the game, most effectively while the city is in We Love The King Day. Your cities are done growing when you have no more tiles to work and no more specialist-slots to fill (but even then more pop usually doesn't hurt).
2. Building infrastructure
This refers to buildings and improvements. Ideally you want every building built in every city and every tile in your empire improved. Realistically you can't expect to get every building done in every city while still keeping up in growth and military. Focusing on hammer-buildings first helps, focusing on growth and gold-buildings after that is usually good, but you have to adjust this to fit the flow of the game. Getting walls up if you expect attacks getting science or culture buildings up if you're not doing that well on those fronts.
3. Military
You need to keep a standing army. Yeah I know that building a military and not using it feels like a waste, especially if you're delaying growth or infrastructure to get it, but you need it. Keeping a garrison in every city and 2 solders near the border just isn't enough with the new and improved AI. The AI will smell weakness and attack, they will bombard your cities in just a turn or two after declaring war and they will keep pushing forward. If you don't have an army up by the time they attack you're not going to be able to hold them off. Of course the defensive army needed varies quite a bit, settling your cities in cleaver defensible locations and making sure your cities are up to date with the latest defensive buildings allows you to hold them with less units. In the end you're probably a lot better off just not getting attacked, and for that you need a respectable military score.
Military is also key for taking AI cities, in CPP you can't (usually) just city back and go for a science-victory hoping that the one snowballing AI is going to ruin himself and not contest you. You usually have to either expand your empire by preying on weak neighbors or you have to slow the beast down by attacking him. A good time to do this is when you hit your unique unit(if your civ have one of those) because they tend to be stronger, making it easier to make an impact.
Siege-weapons are just as important in CPP as they are in vanilla, but you're not going to be able to do that old strategy where you just move a couple of artillery forward with a melee unit or two guarding them, mowing down anything. The AI is going to use fast units and flank you, the AI is going to try and surround you and the AI is going to blast back at you. What I'm trying to say is that you're going to need more soldiers to attack than you did in Vanilla.
4. Science and Culture
Keeping up in Science is key, if your enemies out-tech you you're going to have a huge military disadvantage, you're also going to have access to less production-buildings growth-buildings and specialist-buildings. Your specialists and your tiles are going to produce less yields and in general everything is just going to be slightly worse. Culture isn't exactly as important as science is, but Social polices are a lot more powerful than they are in Vanilla, and wonders can't be built unless you keep up in both science and culture. Another key aspect of culture is that it is a lot easier to lose this game to a tourism-victory than it was in vanilla and keeping up your culture is kinda the only real way to prevent that.
Just growing your cities doesn't provide you with any science or culture at all (before public-schools/museums) so you need to work your specialists. But working these specialists slows down your growth and your infrastructure (and because of that your military) so you need to find a decent balance to run.
In the end that's pretty much all it comes down to, you have to balance these four basic aspects and on top of that figure out a way to outsmart the AI because the AI is also going to balance these 4 aspects.