BTW I have tried to include zsync in the repos but is not really possible (fails to compile / package), which of course I wanted to made a correct package from it, so i think we should just use the manually-installed one or removing the S from the httpS of the repos 
good question, reiser3 was unsable on previous kernels and I assume its more stable now on this new kernel (I did some tests and installs and I didn't had a kernel crash, so I assume it is), stills in any case the best performant option for old machines and the most stable FS ever (no joke 
even ext4 crashes, reiserfs never lost a single file in all my experience and computers and systems)
note that this is version 3 and not 4 of reiserfs, 3 is very old and good, 4 is new with more features but i found a few reasons to not use it in production (slow external disks, and some unstability in multitasking)
@yoda please be very far away from BTRFS, in fact it is entirely banned from the installer because elive loves its users lol check my experience: How to recover from a BTRFS crash / failure
About your other questions, maybe ext4 is better for a workstation (more common and may cache better the files), also includes some SSD features that reiserfs has not, but for any normal computer or even better old computers, i suggest reiserfs (3)
all of them if im not wrong 
