Or is it a subscription?
No subscription. These LUTs are one-time-purchases meaning you buy them once and own a license to use them forever.
The LUTs are all compatible with Davinci Resolve and EOS 70D footage. You can easily upgrade from OSIRIS to the entire Hollywood Bundle later so I would suggest you get the OSIRIS LUTs first and if you want to expand your palette with the additional ImpulZ LUTs you can simply upgrade from within your account later. For clarification the Hollywood Bundle consists of OSIRS and ImpulZ.