AutoCAD .dll to run scripted commands in the background

I'm after a .net assembly that will run some scripted commands for AutoCAD 2014 in the background i.e without opening each drawing. I'm after the following: Draw order above, below or front, back. detach xrefs attach xrefs change xref from attach to overlay freeze layers (layers to be chosen from a dialogue box) thaw layers (layers to be chosen from a dialogue box) change layer colours change layer linetypes I've seen this done before with layer selections brought up in dialogue boxes listing all the layers in the drawing in alphabetical order. The draw order would give you an option to select yes for front and if no then it would send to back.