I have double checked the F-Smash connecting better. This is very easy to test against Ike. Space it mid-distance.
Fthrow and Dthrow have a slight knockback increase (only +1)
Bthrow - 104->104
Fthrow - 98->99
DThrow - 111->112
Uthrow - 83->83
I'm not sure what the "down air meteor" one means, but like most moves there is an increased knockback on the spike of the move.
Dair - 117->124 (both hitboxes, no spike.)
Dair (Spike hitbox only) - 94->102
Or does the question refer to both hitboxes connecting easier?
I tried to test for invincibility yesterday since I was curious if he had total invincibility. What I did is I went to practice mode and put down the spicy curry item for the enemy to take. You can counter the fireballs, but you'll most likely be hit by another one as you approach the opponent with your counter. I'm unsure of if there was an increase in invincibility or not. I can't think of many other ways to test it yourself - maybe the fire flower item would work as well. I can confirm it is not total invincibility though.
I'm very interested to see if the MArts have less down time. I actually took notice to this yesterday, but I threw the idea away as just a psychological effect, since I was waiting for a smash ball to appear rather than being in an active fight. I can test this when I get home though with two 3ds side by side =]. It will probably will be hours until I get home, so somebody else is more than welcome to test this if they can.
I'll also test the down B's timing.