Feats for a Treesinger?

[LibraryRPGamer]

Hi Everyone,

I'm wanting to play an elf treesinger druid for a three man party. I've never played a druid before - I've read all the guides - and I am still a bit lost on which feats to take. So, I've come to the boards to get some assistance.

We are allowed to use anything found in the hardcover paizo pathfinder books. So, no Boon Companion feat since it is in a softcover splat book. Also, no 3pp materials.

We have four people in our group. I will be alternating GM responsibilities with another player. This means that there will be 3 PCs in the party every session -- no GM controlled characters. We have decided to run PFS mods with some house rules (so, not legit PFS; no credit). The idea was to create a campaign with an episodic feel. Also, we will be leveling every other session. This way, both GMs get to run and play at every level. So, I will be playing this druid once per level. We start at level 5.

My character concept is this:

"He is the forest's hunter. For when the ents march to war, this elf stalks their foe and commands the charge"

Basically, I want this character to be able to cast spells and/or fire arrows from the swaying bows of his large tree companion as it pounds everything to a pulp in combat. I understand that the treesinger's wildshape is way underpowered and that's ok by me. I think the flavor of the archetype outweighs its potential mechanical failings. Plus, a caster/archer druid gives me more versatility with only three players. Also, I know most caster druids forgo the animal companion, but, again...three man party...the companion will add some needed melee firepower to an otherwise small group.

Here is where I am stuck: I know which feats I need, but, I only get three. I can't do everything and I need to pick a path and stick with it. Which one do I choose?

We have a 20pt buy for abilities. Assume at least 16s in either/both dexterity and wisdom.

Option A: Archer Druid:

1 - Point Blank Shot, 3 - Precise Shot, 5 - Rapid Shot

Pros:
-- High damage with Rapid Shot
-- great classic flavor (elf firing arrows from a tree)
-- if I need to dismount, my feats will still be effective

Cons:
-- -4 when attacking from moving mount
-- casting primarily buff spells, not crowd control
-- take AoOs when firing arrows while companion is in melee from mount (?)
-- companion has incredibly low AC, so, no Mounted Combat to negate attacks/damage
-- not sure if archery is enough versatility for a small group

Option B: Mounted Caster:

1 - Combat Casting, 2 - Uncanny Concentration, 3 - Mounted Combat

Pros:
-- can cast spells while moving w/o penalty
-- still great flavor (elven warrior commanding the battle from a tree!)
-- When companion is in melee, character would be in perfect position to cast most powerful caster-centered area spells
-- Mounted Combat will negate one hit per round to companion
-- Perfect setup for Indomitable Mount and Trample feats...thus increasing the vitality of the companion.

Cons:
-- companion means fewer spells; what do I do when I run out?
-- take AoOs when casting in melee (?)
-- far less damage output = more dangerous for a party of three
-- combat casting is a waste of a feat
-- if I need to dismount, my feats are inactive

I like option B best. However, I am concerned of running out of spells in the second encounter and being useless for the rest of the day...our group tends to avoid 5 minute work days.

So, which option is most versatile for a party of three?

Thanks for your suggestions!