A freeware progam that I use is called the GIMP (Graphic Image Manipulation Program) it will do much of what the more expensive payware programs will. It should work for what you have in mind. Just google GIMP + image or something like that.
Nothing beats Adobe Photoshop or its much more affordable sibling, Photoshop Elements.
I know for a fact that Photoshop can address both of your issues although adjusting extreme perspective on such an irregularly shaped object such as a building might turn out wonky.
Can you post the pics here so I can see and possibly advise?