Theoretical Question (Architecture)

Short answer is yep :) So a software developer writes the kernel just like they would for other vendors and the compiler generates a hardware accelerator that implements the kernel. In OpenCL speak this compilation is referred to as offline compilation because you are compiling a binary (the hardware image) which your host application will target later. Once the hardware is compiled the accelerator is accessed by the host using the same APIs that you use for any other OpenCL vendor.

So the key difference in the technology is that the compute unit archeticture is not fixed in the FPGA so your kernel is implemented as a custom processing block whereas with ASIC vendors your kernel is compiled into microcode that is then run on a fixed archeticture.