Especially like the 3rd one…. looks like you’d get a good square crop out of it too if you wanted to go that way.
As for the question on the tripod – yes it is one of the most important parts of the landscape photographers kit, as many of your shots will require an exposure longer than it is possible to hold a camera steady. This is generally to allow you to preserve good depth of field in normal light, but you may also want to be shooting in low light situations. A tripod also allows you to intentionlly increase your exposre time to convey movement (water/clouds/windwept grass… etc.) … Not to mention a tripod also allows you to take a more considered/thoughtful approach to composition.