welcome on Kapi Regnum! Let me try to reply to your questions as best as I can!
1. I saw there's a section for ads in my shop but I couldn't find them on the market. In KL the ads are under "Advertisements" on the market but here... where are they?
Ads are called "pamphlets" here on Regnum. So if you go to the market, choose the "non-food-market", then select "pamphlets" to get there.
2. Where can I see how many residential buildings I have at the moment and how many of them have been built? When it's about the dwellings it's easy because their building time is 90 seconds only but when it's about the other residential buildings I hope Upjers don't expect from me to remember the exact hour I've placed quarters or a district on building so the next time I login to figure out are they ready or not?
A regular dwelling takes 2.5 hours to be built, a quarter 8 hours, and a district 20 hours. If you click on your overview "City Hall", scroll a little further down, and you will see "An overview of your city". This will tell you how many buildings you own at the moment, and how many people will be housed in the new buildings that you are currently building, as well as their employment status. On the right hand side, you can see which buildings are currently being erected. Click on "details", in order to see their progress in hours, minutes and seconds.
3. Is there the same thing as in KL when you reach certain level you unlock new things in the game like administration buildings for research, production, building and selling? And if there IS such a thing - can somebody tell me what is being unlocked at every level? At the moment the most urgent for me seems to be the address book which I can't see anywhere in the menu.
Yes, there is. Simply visit the "help" (click the question mark to get there). Under "rank" you can see, which features will be unlocked with which rank. You can also find a list of all buildings and the levels from which they are available in the help.
4. In KL it's easy to make money from Gas (I'm an Oil King in both servers
) because it requires only a small ammount of Oil and Power. Is here such a product which requires only 2 things to produce? For the moment I'm producing goats but they seem to be very slow to produce. And because this game looks like KL in many ways I think I can become Something King here as well if I can find such a "low-requirements" product.
You can also consult the help here. All products are listed there, including the products and raw material you will need in order to produce them.
Please let me know if you need any further advise!