Take a look at the FAQ for the Core Rulebook:
http://paizo.com/store/downloads/pat...y88yj/faq#tabs

Both of these issues have been clarified (or changed, for the HP) since the Bestiary was printed.

Fixed in the next update, thanks for the report.

I'm sorry, but none of the posters in that thread are Paizo employees. I can't base my decisions on what various people think Paizo meant when writing the ability.

I agree that they probably intended to make it "may be taken one time and one more time per 5 summoner levels", but I don't know whether they intended to make it 1st level + 1/5 levels (levels 1, 5, 10, 15, 20) or 1st level + 1/5 levels beyond 1st (levels 1, 6, 11, 16) (I'm guessing the first, but I don't know). Until there's an official change, I have to go with the ability's text as written.

Known issue - this is the bug I need to fix before I can add torches to the In-Play tab.

Fixed in the next update, thanks for the report.

Would you mind sending me the file in question, please?

Hmm found the official post, but it's more odd than I thought. Here is a quote from Paizo Employee Josh. link: http://paizo.com/paizo/messageboards...paizo/eidolons

Joshua J. Frost, Thu, Mar 4, 2010, 02:27 PM

As for the Improved Natural Armor evolution, that last sentence is unfortunately not very clear. Here's the intent and how you should handle it until the class is finalized:

The intent was that you could take it at level 1, level 10, level 15, and level 20. So it should read something like, "This evolution may be taken once for every five levels the summoner possesses, minimum level 1." So you could take it at level 1, but then you'd need ten summoner levels to take it again (level 10), 15 summoner levels to take it a third time, and 20 summoner levels to take it a fourth time.

Hope this helps!