A standard spell is generally used at a distance the caster can clearly see his target (about 50m or so in an open field) and will affect one target and if the effect is not instantaneous it will last for the remainder of the scene.

All of these things are governed by the effect of the casting roll, just like the primary effect of the spell. Moreover, they can be traded for each other.

So if the caster wants his spell to affect multiple targets, he can do so by either rolling a critical success for increased effect (raising the area or target to a group) or by reducing the primary effect.
The most common trade-off being affecting a group (larger area) but with a reduced effect.

Take the following table as a rough guideline. Note that duration does not apply to spells that cause an effect and immediately end, such as most harm or healing magic.

For the duration it is important to keep in mind that the effect governs the total effect caused by a spell. So a protection spell of standard effect will provide one box of protection for the duration of one scene by default. That is one box for the entire scene, and not one box refreshing every combat round or something like that. A simpler way to look at it is that the magic ends once its effect has been fully applied, even if it has hypothetical duration left over.

The caster can usually end a spell with duration prematurely at will, as long as the target of the spell remains within range. This is worth to keep in mind when trading range down to touch for easy higher effects. If you shape-shift your companions that way, you need to touch them to change them back, or wait until the full spell duration is reached.