Photoshop is for editing. That won't be of much use. Stick to Lightroom. simple and amazing
Yes worked on that and below are the results with comments
yes the f/2.8 shows that it was Tamron. IMO I have noticed that the 18-105 has better picture optics and quality than this. This is my review, I'll have to use it to comment further...
So these are the images you sent. I uploaded via my flickr because it makes posting easy. Due credits are given 
Image 1:
- The Noise on this image was too much because the ISO on this one was 5000 which is HUGE. NEVER go beyond 3200. Be creative with ur settings but never go beyond 3200. For me ISO 1000 would have been enough.
- Keep the aperture for landscape or such shots where the subject is not there or everything is the subject at around f8 to f9.
- sinch the grain was too much, post processing was not much fun.
- did a bit of white balance correction (not needed though)
- increased the clarity, did some changed in highlights to bring in the shades and decreased the shadow to show a bit color of the rust

Testing 2 by Yawar Masood, on Flickr
Image 2:
- everything was fine abt it, the ISO, shutter
- shot needed to be done at f7 to f9 IMO
- improved colors in the sky by turning the white balance more towards bluish shade
- improved outlines in the tree by increasing clarity

Testing 1 by Yawar Masood, on Flickr