Is kernel a process?

Question

1. In Linux, we always say the first process is init(pid==1). but why is not the kernel(startup) which setup the system and create init process. Is kernel a process?
2. We know all the user space threads are rooted at init process. then what about scheduler and other kernel stuff, like memory management?

Basically, what confuses me is the structure of the kernel, if is a process, is it a single process or consists of multiple processes.

Thanks in advance!