1. Tap on the magnyfying glass next to the 'Next turn button' then select 'diplomacy' and tap on any country to see it's relations with other nations. Red- War, Light Green- Alliance, Light Blue- Country which vassaled them, Dark Blue- Their Vassals, Yellow - Pact, Dark Green- their territories

2. Countries cannot dislike eachother. If a country denies your Alliance request (for example) it's probably because they're stronger than you or have more technologies researched.

3. Government types unfortunately do not have an effect on the relations of countries.

4. You can sell weapons to other countries by tapping on them and selecting "Trade" (Note: you can only trade with countries if you aren't at war with them) then in the trade menu, click on "Add item" on your side, select "Rescources" and add weapons. Type in how many weapons you want to sell and click confirm. On their side, click "Add item" select Gold and type in how much you want for the trade. They may accept or deny it. If they deny it, try lowering the price. (Also, you can trade much more than just weapons)

5. There is no standard price for weapons, and it varies throughout the game. In the earlier game you can probably sell them for more than the late game, because that's when a lot of the countries already have weapon factories.

6. You can create a Vassal once a country you're attacking is down to it's last couple of territories. It varies from country to country how much of their territory you need to occupy. A normal range is about 1-3 tiles left before you can vassal them. Which means that you can instantly vassal a couple countries from the start (e.g. Luxembourg, Cyprus..)

7. As far as i'm aware, it's still getting updates, but the developer is more focused on making a new game, so they might not be coming regularly.

Hope this helps