Right ok on #1 your shutter speed was a touch to slow (only by a couple of secs) - HOWEVER, if you got it right, the shot would have turned out like #2.

The reason why your shots are coming out like this, is because of your cameras metering system. It cant meter the forground and background in such extremes of light and dark. On #2 your camera has metered from the sky, and has set (or you have) the settings to obtain the correct exposure for it. Thus, the forground being dark but the sky perfectly exposed.

Its a similar story on #3. This time the exposure has been set for the foreground, resulting in your sky being blown out.

The best way to fix this without any extensive editing, is to buy a ND filter. Its a dark gradient going from the top of the lens, claring as it goes down. This will allow you to expose the forground and keed the sky from blowing out too! Another way is to take 2 shots, one for the foreground, and one for the sky, then merge them in your editing suite

You must remember a camera doesnt work like our eyes do, and it does have limits. Its always helpful to understand how and why your camera works the way it does, as you can then determine better what kind of results you can achieve.

HTH
(just to add a fill flash is faily pointless in landscape shots )

Nice tip KK!

It all just takes a lot of practise Stormey, the key is to keep on it - least that's my plan