This covers obtaining the ISO, connecting to Wi-Fi, partitioning, formatting, mounting, installing, setting up encryption and installing GRUB, in one article. Also includes some tips, like quickly mounting from install medium. Maybe this helps someone.
The Bootloader itself cannot be encrypted afaik, but the Kernel and initrd can reside on a LUKS Volume (GRUB_USE_CRYPTODISK). But, in order to prevent having to input your passphrase twice, you need to use a keyfile, and I have no experience with that, so I have gone another route. I don’t think that a kernel and initrd necessarily need to be encrypted