Ok, Water release is one of the basic elemental nature transformation in the narutoverse that allows the user to control pre-existing water or create their own, by molding their chakra into raw suiton chakra by of course using nature transformation. It is also one of the most versatile of the five basic chakra natures, Water Release techniques can not only change shape but state as well. Moreover, the water can become more solid in the process. In battle it can be utilize for many thing like making fogs so that the user can assassinate their opponent, it can be a good defense against fire attacks for water is stronger against fire and it can also be good for offensive attacks like the water bullets etc, which can impact damage to the enemies body for the speed at which the water will be going. Now for the strengths and weaknesses, like i mention before water is strong against fire for it can simply cancel it out, but if lets say it is going up against a fire technique that is of high rank then it will probably just cause an evaporation. Now for the weaknesses, water is solely weak towards earth because earth structures can dissipate the force of water rendering the technique ineffective. "Some combinations of water techniques?" by that i'm guessing you're referring to KG so let's see. well i believe you have ice release (water and wind), Wood Release (water and earth), Storm Release (water and lighting) and Boil Release (water and fire). And now for some useful effects that water might make when clashing with other elements. Well for wind when water is clashing with and equal ranked wind it will just cancel it out depending on the tech, Earth - it would simply absorb water, depending on the ranks and the tech, Fire - well again like i mentioned before clashing with fire would extinguish it, where as it would also produce steam upon contact, and for lightning it would surge through water and electrocute the user if he's in contact with water. What are various ways that water can be created outside the normal means of releasing out of the user's body? well it's simple you can use an existing water source and insert your chakra into it and manipulate the source to form your techniques, these are techs which state: requires a water source to use. You can also materialize water out of thin air, by sending your water chakra into the atmosphere and forming whatever you want out of thin air.