Simple Q&A D&D 3.5 (by RAW) XXII

[rockdeworld]

A200
Yes. Nothing restricts it from magic items, or restricts it to prepared/spontaneous spells.

A206
Yes. You can apply Saint to a Living Construct (eg. Warforged, and Saint Dragonborn Warforged is a powerful, cheesy race). A living construct is a living creature with a Con score, a regular construct is not with Con -.

Constitution: Any living creature has at least 1 point of Constitution. A creature with no Constitution has no body (a spectre, for example) or no metabolism (a golem).

A208
Yes, you have 1 swift action, 1 move action, and 1 standard action per turn (or 1 swift action and 1 full-round action), so you could cast Swift Expeditious Retreat + another spell that requires a Standard or Full-Round Action to cast.

You can perform one swift action per turn without affecting your ability to perform other actions.