OK, so please keep in mind this will be my first DIY project indoors (i usually stick to the outdoor stuff). I plan to replace all of the sheetrock window jamb extensions with wood and then trimming out the window with casing. I believe I have the necessary tools (Air Compressor, 16ga Finish Nailer, Compound Miter Saw). I just need some basic help to get going and anticipate what all this might entail. I already anticipate having to redo the sill because I don't think it will be wide enough after I add my casing. I'm sorry if there are many other threads on the subject but none seem to address removing the old sheetrock from a newbie basis which is what I need. So here are some questions I'm thinking about
-Do I just take a hammer to the sheetrock window extensions and punch a hole and then pull off the remaining sheetrock? What is likely to be behind the sheetrock?
-Do the Sheetrock extensions typically project all the way out to flush with the main wall or does the main wall sheetrock extend all the way and then there is a shorter extension piece. (basically where do these pieces typically come together - in the extension or on the main wall)?
-Also, the width of the extensions is a little less than 4" so will I have to rip the new wood extensions out of 1x4? I don't have a table saw or circular saw so I'm wondering the best way to accomplish this.
-Also the thickness of the drywall vs the thickness of the new wood extension jambs (do they need to match)?
Can someone give me a basic step by step of how to tackle this?