For your Summoner specific merits question, I initially went with the 5/5 on physical accuracy and physical attack back prior to them adjusting what Summoning Magic Skill did. Since the change to how that skill works, and the boosts that our magical bloodpacts (the merit bloodpacts in particular) have obtained, I took out the 5 in physical accuracy and put them into the magic attack instead.
For the merit bloodpacts themselves, I unlocked all six of them (since I like being able to exploit any elemental weakness a mob has) and then divided the remaining merits up equally between Wind Blade and Heavenly Strike.
For the attributes section, really there's nothing there that you need to boost for your Summoner (attibutes for yourself don't translate over to your Avatar), and should you level a melee job at any point, you'll probably want to cap out STR.
The combat skills, magic skills, and others also come down to what else you may want to level in the future. If you only planned to do Summoner and nothing else, then sure, evasion boost and staff boost would be acceptable if you wanted to be up there with your avatar meleeing or something. But if you plan on leveling something else, then you'd probably be better leaving them alone for the moment. Likewise, if you don't plan on leveling a tanking job at any point then the -enm would be fine. Spell interruption rate is a good merit choice, because regardless of whether you're a tank or a mage or a melee with /nin or something, if you're in a position to where you're casting magic, then that'll help you.
I went with a full 8/8 Summoning Magic Skill because my only other Mage job is my Blue Mage (I have Brd as well, but I'm able to hit the current skill cap on songs with just gear, so there's no real value for me to merit it currently). Having that additional 16 skill helps out quite a bit as far as Bloodpacts (accuracy and magic accuracy for Rages, duration and potency of Wards), Avatar's Favor (potency of the favor effect), and Elemental Siphon.
Lady Jinte wrote:
Vlorsutes' Negotiation Skill rises 0.2 points
Vlorsutes' Observant Parent Skill rises 0.3 points
Vlorsutes' Argument Diffusing Skill rises 0.1 points