Hello there Artixnok!
First of all welcome back!
There are enough players on the F2P and also on the P2P if I´m not wrong to do content like raids and PvP. On the F2P it´s easier since BG pops quite a lot especially in the evenings. There´s Sunday 6v6 Domi and Wednesday 12v12 Dominion.
For the topping up it kinda depends on what you want in game. Like if you want to be top player yes you would have to top up. If you just want to have fun with friends and play casually you don´t have to. There will be some offers when you hitting a certain level for some higher runes for example. Also you can drop perma items up to epic now in Astral.
On the P2P you only have to pay for the subscription. And from what I can see there are some turkish players on the Empire side at the moment (Not sure about League side tho).
Hope that helped for now! Don't hesitate to ask other questions if something not clear!
Greetings!