Maybe. Maybe not. There is no plan.
Maybe someday. Maybe never. If you want to see something happen, you can do it yourself!
There are no ISO images. This project does not cater to non-technical users.
Simple, my friend! Just refer to the build instructions.
The system was originally 32-bit only, since that's what Andreas was most familiar with when starting out. Nowadays, there is a 64-bit port as well (Intel/AMD x86_64)
If it builds on CI, it should build for you too. You may need to rebuild the toolchain. If that doesn't help, try it with a clean repo.
If you can't figure out what to do, ask in the #build-problems channel on Discord.
The SerenityOS project tries to maximize hackability, accountability, and fun(!) by implementing everything ourselves.
No, SerenityOS does not have a package manager. The project uses a monorepo approach, meaning that all software is built in the same style and using the same tools. There is no reason to have something like a package manager because of this.
However there are ports which can be found in the Ports directory. A port is a piece of software that can optionally be installed, might not have been built by us, but supports running on SerenityOS. They act quite similarly to packages, each coming with their own install script.
Currently when running the system in a virtual machine, ports need to be cross compiled on the host, and added to the file system image before booting. Then it's also possible to configure the build system to in- or exclude components from a build.