And to remind you guys that more posts would be appreciated, and to clarify something that I think I've mentioned, but which you might've forgotten, have an info update!
Language and Telepathy
Telepathy is language independent.
This means pretty much exactly that. Any (human) can in principle 'talk' with any other human, as long as they both know telepathy. Telepathy as it happens is pretty simple when restricted to line of sight, so in magical societies, it's commonly the mainstay of merchants, explorers and travellers.
The problem is that constant usage isn't actually all that healthy. The TSAB has a lengthy list of mental illnesses associated with overuse of telepathy, and risks are increased when the involved parties don't know the same language, because they have to 'interface' at a deeper level. On the other hand, telepathy can greatly accelerate language learning - specifically vocabulary.
The upshot of this is that as long as you can convince people to use telepathy, you can talk with almost anyone. The risk is that without knowing the language, you're going to be 'exposing' yourself a lot more than usual, which makes it easier to tell stuff like emotions, and often makes deception very, very hard. Unless, of course, someone has specialized in the field. "1x Telepathy" does exist.
Magical Civilizations and Warfare
Basic magic-using civilizations can actually reach a fairly high 'technological' stage of warfare pretty early. Ranged-attack magic and telepathy mean that most magical societies can manage stuff comparable to early WWI warfare, sometimes even higher, despite very low industrialization. Often though, they stagnate around a tribal style of warfare dominated by B-rankers and above, who form a permanent 'caste' of professional warriors, since the dissemination of magical knowledge is difficult without formalized logic and computing to describe the basis, much less the key mathematics required for industrialized magic.
The really big deal is telepathy though. Usually, nobody figures out how to use it better than just line of sight, but sometimes focus materials and frequencies are discovered, allowing for primitive radio equivalents, or simple transmitter/receiver relays are developed by accident. Often these inventions drastically change the social and cultural development of society, in particular vastly increasing the degree of centralization.