As for subjobs: You need RDM as your go-to sub, and if you plan on doing abyssea content, you need BRD. Other subs are situationally useful but not terribly important.
BRD is useful for, and only for, yellow-staggering NMs in abyssea. BLM/BRD has every BRD stagger available to them (although it loses dispel from RDM), and can easily land songs with elemental seal. When ES is not up, sometimes using the right atmas and gear is enough to land songs. A lot of people may disagree that this is a *required* subjob, but if you are serious about BLM, you should really have this subjob leveled by the time you get high enough to do abyssea. Your linkshell/pick up groups will thank you for it.
WHM can't hurt to have, for traveling if nothing else, but RDM is almost always superior for everyday use.
NIN helps for soloing at low/mid levels before you gain the survivability from RDM and WHM. It's far from needed, especially if you level in a group.
For equipment: Everything you listed is good. I might recommend the relic hands for dark magic. While you're leveling, igqira/genie gear at level 70~ is nice to pick up. I still use the legs and head for enfeebling. The body is nice for nuking but will be replaced. Pick up the elemental/enfeebling/dark torques when you can. The elemental one will eventually be replaced, but it will serve you until then. Until you get to af1 level, just stick in INT gear where possible. Upgrade INT rings when possible. Use elemental staves and never take them off from 51 onward. They won't be replaced until if/when you make the ToM versions. For straps/grips, I use bugard leather +1, macero, and whatever the dark skill one is called. Noteworthy accessories at 90 are the Goetia accessories, the cape turul drops, witchstone, hectate's earring, siegal sash (sp?), and probably a few other new goodies I'm forgetting.
Edited, Aug 3rd 2011 1:14pm by RizzoRazzle
~SMN99 BRD99 BLM99 BLU99 WHM99 DNC99 THF99 RDM95 COR95 SCH95 RNG75