1) Don't use Bloodshed Dev-C++. That product hasn't been supported for a number of years now. Use wxDev-C++ (or wxDev-Cpp it maybe called). This will also provide you with the ability to build GUI forms for wxWidgets
2) Pick a good GUI toolkit to use. wxDevC++ is built around wxWidgets. But there is also QT, GTK and many others you could pick.
Not really. Depending on the GUI Toolkit you pick they each have their own style of building and working with the UI :) wxWidgets is a fairly good one to start with.