Upgrading automaton:
http://wiki.ffxiclopedia.org/wiki/Pu...Your_Automaton

Info on automaton heads, frames, skills, spells, and attachments:
http://wiki.ffxiclopedia.org/wiki/Automaton

Attachments are kind of like scrolls for other jobs. Once you trade one in, you have it forever to customize your automaton with. All attachments can used at level 1, though some are very pricey.