To answer the second question first, there are several assemblers available for Linux, the two most prominent being gas (the standard GNU assembler, which is required by gcc and comes part of any Linux distribution worthy of the the name) and the Netwide Assembler (
http://nasm.sourceforge.net/), better known as NASM. While gas is installed on just about every Linux box there is, NASM has become quite popular, as it uses the more common Intel syntax rather than the AT&T syntax; also, it is better suited for hand-written assembly code, since gas is meant primarily as a backend for gcc and has weak support for macros and structures, poor error messaging, etc. If you prefer the Intel syntax, NASM seems to be the nearly-universal choice these days.
As for a simple cookbook list for OS design, well, there's no such beast to the best of my knowledge. OS design is both very complex, and can be approached from several different angles. Ironically, most people agree that writing your own bootloader is a Bad Idea, but it seems to be where just about everyone starts off. This includes myself, but then again, from my perspective I'm not writing an OS yet, I'm just practicing to get ready to someday.