So, the Synthesist variant of the Summoner lets you bond with your Eidolon rather than call it separately, however I've got a couple of questions that the SRD doesn't define:http://paizo.com/pathfinderRPG/v5748btpy8k8r/faq
1) When fused, do you still keep your gross physical characteristics? eg if I'm a human and I fuse with a Serpentine Eidolon, are my own arms & legs functional? And if yes, does that mean that I can use my base land speed rather than the Eidolon's?
2) If I "Gain the Eidolon's HP as temporary HP" am I able to use heal spells to 'heal' these if my temporary HP get damaged? Otherwise I have no idea how the Eidolon could be healed.
3) Do I get the Eidolon's saving throws? I'd assume no since it's not specified but otherwise I have no idea why they'd even be recorded.
1. nope unless you take appropriate evolutions.
2. nope. rejuvenate eidolon spell is not working by RAW, however allowed by the same faq. otherwise - you have no eidolon, there's nothing to heal.