So I'm playing a summoner that's based on the SLA ability, with the Master Summoner and Evolutionist archetypes from UM. My eidolon is basically a personal knowledge bank, with every evolution going towards Skilled: One Knowledge or Another. It's a nice change from my primary mounted summoner (long story).
My question is feats. What feats would you suggest? Skill focus feats just seem like such a waste. Additional Traits has potential, but I'm getting lost in the vast quantity available. Anything from Paizo should be acceptable.
The character is only existing for level 6, maybe 7. Thus, the eidolon will only have 3 hit dice for its existence.
I'd suggest bumping its use magic device skill, via feat and/or evolution; having your eidolon back you up with wands and scrolls would be really handy.
I like the concept of your eidolon. I'd expand on it if I were in your shoes; give it ranks in craft/profession skills and have it make stuff for you and the party!
Feats are tricky, because 90% of them revolve around combat, and your eidolon isn't a fighting type. I'd suggest feats that help keep it alive and available; dodge, the save boosters, perhaps run. Extra traits is good for adding some minor bonuses. Toughness is always a good choices, especially if your eidolon is going to be only half your level.
If you can talk your DM into Breadth of Experience, that might be a good idea, as it gives a +2 to all your knowledge skills.
UMD will be very useful to you, as it gives your eidolon something useful to do, and it fits with the knowledge battery you have the idea for.
I would also make your eidolon small, for defensive purposes. And for flavor. Who doesnt want a small deformed henchman with useful tips that you claim as your own ideas?
Extra Evolution from the UM seems like a good fit for your character as well. At least I remember that spell being in there, have to go from memory.
Improved natural armor or Dodge can be somewhat useful, unless you like throwing your eidolon under the bus as it were when you don't need him anymore.
At level 5, I would suggest this strategy. Make your eidolon good at UMD, and use the rest of your evolutions for defense or something similar. Then make a wand of Lesser evolution surge, and have him give the skilled evolution for whatever knowledge skill he might need at the time. Then he can still do everything you ask of him, as well as a few things more.