Two Summoner Synthesist Questions

[Thomas Elfing Johansen]

I'm doing a Summoner Synthesist for a forthcoming game, and I have a couple of questions, I hope you guys can help me with.

And yes, I've tried searching other threads for an answer and have come up blank.

How do I calculate hitpoints for my Summoner? If my Summoner has Con 10, and then changes to a Quadruped with Con 13, does he gain +1 HP. And what happens with this one extra hitpoint it the Eidolon is slain or banished? This can become fatal for my Summoner if I choose to use Fused Link.
It clearly states that: "While fused with his eidolon, the synthesist uses the eidolon’s physical ability scores (Strength, Dexterity, and Constitution)..."

Next question: Do I (I being the Summoner) gain the Quadrupeds movement (40 feet) instead of my own (Human, 30 feet)?
It states that: "The synthesist also gains access to the eidolon’s special abilities..."

That's about it from me, for now.

Hope you can help me.

[Jason Beardsley]

HP: Ja, your Con jumps up to 13, giving you +1 hp/level. Then you add your Eidolon's hp to that total, treating his hp as temp hp.

Speed: Ja, you gain 40' movement

Edit: I have a player that decided to make a synthesist, since I'm starting them off at level 10, it's kind of disconcerning to see how ridiculous his character gets when he summons his eidolon. But, I want to give it a try. I'm thinking it won't be as bad as I'm assuming =)

[Mojorat]

say at lvl 1, 10 con you have 8 hp. your eidolon has 13 con.

when you fuse woth it, your con becomes 9 ( 8+ new con of +1) and you gain 6 temp hp. (average of d10 +1 from con)

you gain any ac movement modes water breathing etc the eidolon has.

[Ronin72]

I wonder if the summoner takes the feat Arcane Strike would work for the Slam attack???