You can use VidIq extensions for keywords research, but I really suggest a product from a seller here: "video marketing blaster pro", it's quite amazing and 1 time payment. For thumbnail, you can use photoshop but I recommend Canva if you don't want to waste much time and get almost the same results (even better because you already get prefab templates)
Well use vidlq free version but they give not much information on free one. :/ Well i will take look.Yeah i will use photoshop for that because I'am quite good at it. And what about masking my affiliate links is it good to use bit.ly or goo.gl or i have not so known shorteners?