Printrbot simple metal is a good entry level machine, and as for first layer bonding without a heat table, just need to make sure to set the head close enough to the table so you get a good first layer bond to the plate to build upon.
As for software, you can download these to get you started
Download Repetier – A free software for communicating with your printer through your computer.
Google SketchUp – The easiest way to draw in 3D… and it’s free!


As for working in steels, lets just get this out of the way, and much cheaper/faster to produce via  CNC machining, since the cost of steel powder and time it takes to produce as a lot greater in the 3D printing process.



As for 3d printing, the machine is only as good as the G code you enter into it to print, and truth be told, all the work is in the Cad/cam programing to get G code to send to to the machine so it will print (where you will spend most of the money on software instead).

As for 3d software modeling, here is a list of free and commercial software, and before you can print anything, it the cam programs that have to be mastered first,
http://www.3ders.org/3d-software/3d-software-list.html