A good reference for a social spirit summoner is Umaro's
Spirit Medium.
Force is basically how powerful a spell or spirit is. A spell's force typically influences its effect. For example, a stunbolt's base damage is its force. Force also caps how many hits you have on your roll. If you roll 6 hits while casting a force 5 spell, you effectively have only 5 hits since you can't have more hits than force. Force also determines the amount of drain you take from casting the spell.
For spirits, force determines a spirit's statistics. The higher the force, the higher the spirit's statistics. Force also gives a spirit powers. Every 3 full points of force (i.e. at force 3, 6, 9, etc) allows the spirit to have 1 optional power. Force however affects how hard it is to summon the spirit (since it rolls force to resist your summoning).
Some general advice is to focus on your magical power. It's what you bring to a group and it's a very nice thing to bring. I'll increase your magic to 5. That's the highest you can raise without having to pay more so it's a good place to stop. As a Shinto mage, you use Charisma to resist drain (by far the largest check on your power). Therefore you want a very high Charisma score since you'll be making a lot of Charisma + Willpower Tests. This also synergizes well with being an elf. I would raise it to 7.
As for skills, your main attack is going to be combat spells. I would remove your combat skills and buy Spellcasting. Spells are pretty good.
I actually recommend being a full magician. Mystic adepts are pretty good, but they can be tricky to build correctly. Full magicians are much simpler to do.
