Tree of Savior when and if it gets a release over here? Then you'll be happy to look through the latest community Q&A, which has been helpfully translated into English. Like most community addresses, it covers a variety of different topics, ranging from casting spells on the move to working with companions in the game.
Not all spells in the game can be cast while moving, depending greatly upon the type of spell and the class using it. Similarly, there's been discussion about which classes, if any, will be allowed to dual-wield. Companions can be stored at the barracks, allowing you to choose between several different companions based upon the situation, although not all companions will have the same degree of closeness with a given character. For more information, peruse the full set of answers.