You are using a resolution of 0.2, so you are going to get 5 lines per mm.
If your laser is focused it is likely 0.1-0.15 diameter meaning you will get some gaps, so the solution is either to de-focus slightly to blend the lines or use a higher resolution (say 0.15).
Now regarding the size, when you save an image it doesn't have any physical size. It has pixels. So in Photoshop when you say it the "size" is translated based on the DPI, so you would get 305 mm X 240 DPI = 305 X 9.45 = 2882. When you load it to T2Laser it is converted back to a physical size based on the resolution, so using 0.2 would be 127 DPI, so your image becomes 576mm (2882 / 5).
So, if you are going to use 0.1 for resolution set the DPI to 254.
Better yet, save it at 100 DPI and set the output to what you want after loading. T2Laser will re-scale it using an anti-aliasing algorithm which does a good job of keeping quality but helps provide a smooth engraving. It is also a more manageable file size for generating the g-code.