Rolling up a NPC Tengu Vampire Ninja and was wondering about the natural attacks and their to hit. Does the Tengu Vampire using a full round action to attack get the slam being at full BAB while the bite is at -5? or is it both at Full BAB?
There is this a non pathfinder variant that replaces Sword Trained for 2 claw attacks at a d8, the Tengu Vampire would then have a slam attack, 2 claws and a bite and I want to make sure I am doing the attacks correctly.
Variant webpage
If you have multiple primary attacks, you use your full base attack bonus for all of them. Bites and slams are both usually primary attacks. As the vampire template doesn't say otherwise, it's slam attack should follow normal universal monster rules, so it's a primary.
So...yes, you get full BAB for all your natural attacks.
As for the variant, slam attacks are usually using the hands or arms, so I'd say you'd have to either go bite-claw-claw or bite-claw-slam.
I recommend taking a look at the way the Summoner's Eidolon handles claws and slams based on how many limbs it has. While by RAW it appears you can combine all these attacks, there's a case that can be made on RAI for preventing some of them depending on whether you think Eidolon rules reflect overall intent on natural weapons vs. strictly the internal balancing of the Summoner class features.
Ultimately I think the best deal breaker for you will be whether or not this many attacks will be overpowered when used on your players. At any rate I think this is pushing it for the most possible attacks on a humanoid creature without class levels, which is amusing if nothing else.