The accumulator requires an RSA modulus of unknown factorization, so we used the RSA modulus of unknown factorization from the world renowned RSA factoring challenge.
We implement zerocoin, not zerocash. And yes, we said generating transaction is less than a second, with verification time less than a minute
There's only a handful of even modestly secure primes p and q from that list, from 1536-bits to 2048-bits, with which to use to get N = pq. Key lengths of 2048 bits are unlikely to be secure within the next 5-15 years. As far as I can tell, whoever factors these first gets to spend all your zerocoins ever. It's also totally and trivially quantum insecure due to Shor's algorithm.
That you admit proof verification is measured in single to double digit seconds means that both DDoS of a node is trivial and block verification time is insane; you just need to spam invalid proofs from a number of unique IPs to computationally knock a node off the network, and generating a block with more than a few transactions will be an impossibility to propagate throughout the network before another competing block is published, resulting in massive amounts of orphans and a totally insecure blockchain. You could store the verifications over time in a cache, but it's incredibly easy for an attacker to simply not publish these and then publish a block with say, 200 valid zerocoin transactions and totally screw up the network.
That you're not even storing the niZKPs on chain is another huge problem affecting network consensus based on history.
Hm, do you have good reading links so I can understand this? No work until monday, so there's some time

With their plan of becoming a sidechain to vertcoin, could it be possible to retain some form of security post 5-15 years, assuming the transfer is possible?
With the increased verification time, would ddosing something like a centralized pool become trivial, or is that something separate?
What historical information can be garnished from storing the niZKPs on the chain?