If a temporary Ward is breached, does it collapse like an Evocation Block? or does is lose strength as it is repeatedly breached, eventually grinding it down to zero?
A ward has to be taken to -4 to be "permanently" destroyed before its duration is up. Otherwise it's simply suppressed for a short period of time...generally one exchange per shift in combat.
Is it possible to make a brittle Ward (Low shifts of protection) backed by a powerful magic trap? Or does the Ward have to be strong enough to "support" the attached spell?
Sure. It's also possible to suppress a portion of the ward without taking it down entirely.
Does a blindness spell count as a block against all actions, or just as a maneuver to place the Blinded aspect? Or does the block allow for the Declaration of a Blinded Aspect on the target, for double the fun?
Could be maneuver or block depending on exactly what you're trying to accomplish. I generally go with perception block in combat (similar to a veil but applied to a victim).
One thing to remember with blocks - anything they're blocking can also be used to break them. You could create a block which blocks (almost) all possible actions but it probably wouldn't be simple blindness. It'd be something like being encased in solid earth. Your spell trappings decide specific effects.
Edit: Here's a breakdown of a ward recently used in the game I'm running.
The ward totaled 28 shifts. Breakdown follows:
- Duration of a mortal lifetime, 12 shifts
- Basic barrier / suppression effect rating / power 4, 4 shifts
- Enervating Drain (persistent block against movement), 12 shifts consisting of:
- Trigger (entering uninvited), 2 shifts
- Three zones (hall & entry, living room, stairs), 6 shifts
- Persistent movement block rating 2, 4 shifts
They suppressed the basic ward effect for short periods by beating the number of shifts in that effect. Excess shifts extended the suppression by one exchange per shift. To take the ward down permanently, they'd have needed 32 (28+4) shifts.