May I guess you are from Germany (Because of the name you choosed)?
There are many things you mentioned which you might understand better after a few days of playing.
At first, the base has many important features. You build your Tracking Sattelite, Baracks, Assembly Plant and Warehouse there, thus the base is your important place to pruduce soldiers, produce items, store items, and collect resources remotely. Additionally, your bases level regulates how many soldiers and resources you can store.
Secondly, you advance your range to collect resources by the use of items produced in the assembly plant or with a little chance scrapped from barcodes. So no need to enter someone elses backyard
The way fights work at the moment might be a little bit confusing, but you have to consider that you could attack anyones land within the radius of 100km from your base. You only have to see this land (have land near to it, track the player or be near to it physically). In bigger cities you might encounter the need to attack enemy lands or defend your own earlier as you wish.
Lastly, if you zoom out you will see binoculars popping up for every country showing the top player, how many lands and how many km²s he has captured and the same for the country in total.