look, it's actually fairly simple.
If you summon a spirit and ask it to fight for you that is one (1) service.
The spirit must fight to the best of it's ability. Which means it will use it's powers and spells to achieve the most efficient results (NOTE: the tactics the spirit uses MAY be entirely different from the tactics you wish, depending on how you worded your request!) IF the spirit chooses on it own accord to cast a spell or use an ability, that does not count as an extra service.
IF during the combat you ask the spirit to use a specific ability or spell, then you are requesting an additional service. and that will consume one (1) service owed.
AS to over lapping blast effects: this is the rules and what is listed under each item:
SR 5 pages 182-183 Bold and underling by me
Blast Effects
Grenades, rockets, and missiles are area-effect weapons,
meaning that their blast affects a given area and
any targets within it. The farther away the target is from
the explosive’s final location—the blast point—the less
damage it takes, because distance reduces the effect of
an explosive’s blast.Different grenade, rocket, and missile types lose
blast effect at different rates. Consult the Grenades/
Rockets/Missiles Table (p. 435) to find the projectile’s
Damage Code and Damage Value reduction rate.
There is no mention of spells, or spell effects.
now, we look at multiple blasts:
SR 5, page 183 bold, by me
When multiple explosives detonate at once the effects
are similar to those of a blast in a confined space (more
chunky salsa). When two explosions occur on the same
Combat Initiative Score and both blasts effect the same
character add half the value of the lower DVs to the
highest DV and apply it all as a single modified Damage
Value for the purposes of Damage Resistance tests. For
AP calculations, use the best AP and improve it by 1 for
every additional explosion.
It clearly says Explosives, (not Explosions)... Do we really need to list what is an explosive and what is not?
SR 5, page 283
...The test is like that for grenades (p. 181):
a Spellcasting + Magic [Force] (3) Test with scatter of 2D6
meters. Unlike grenades, you get to add your net hits on
this test to the Damage Value of the spell, but only if you
beat the threshold; otherwise the spell still detonates, but
the hits are used to reduce scatter by one meter per hit....
They have gone through a lot of trouble to tell you that AoE spells act like grenades for scatter purposes... but make NO mention of confined space rules, or overlapping detonation, or "chunky salsa"
Spells also affect everything with (force) meters radius from the detonation point equally, unlike grenades that do LESS damage the further away from the detonation point....
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One of the biggest mistakes many people make with magic is they try to apply scientific laws to the effects. YOU CAN NOT DO THIS!!! Why? Cause it's magic! Magic breaks all the scientific laws, and follows it's own magical laws. The two are rarely the same.