It is a great idea to double check with the rule book for your track. Typically the rules allow racers plenty of time to switch to newer certs, and the SA2015 Conquer Helmets will be good for years to come!
See the below link for more information on Snell's SA2015 cert:
Here is a link to the Helmet Certification Lists on the Snell website:
Here is the difference between SNELL and DOT certifications:
Regarding whether Conquer helmets have HANS restraint mounts, SA2015 helmets must be equipped with FIA 8858-2010 compliant M6 terminal mounts for frontal head restraints. Therefore, all Conquer SA2015 helmets do indeed have the mounts.