Doors and Windows - Replacing Old Casement Windows

Hello,
I have wood casement windows in my home (house was built in 1974), and I want to start replacing them. I have vinyl siding, and brick moulding outside. What is protocol for replacing? What do I do w/ the brick moulding? How do I make up the space difference between the window and siding where the brick moulding was?

Also, is it typical to replace them with new -nailing flange windows? Is it tough to work around the siding with a nailing flange?

It depends on whether the original windows were installed using a nailing flange or not. If so, we usually have to remove the siding and remove the windows, replace them, and replace the siding. Not unsurmountable, just alot of work. The window, frame and brick molding will probably be a unit, and will come out together. Your new windows should have brick mold attached, or in a kit with the window. If you have to remove the siding to get the old windows out, then, yes, install new windows with nailing flanges. It is easier.

What if I want completely maintenance free windows, is there any way to not use brick moulding on the new windows?

You could install vinyl windows with vinyl brick mold. They will replicate what you already have, and will be maintenance free. Vinyl clad windows also come with wooden interior parts if you wish.