Indeed, no JVM. On the other hand, Sailfish OS is a full blown GNU/Linux under the hood, so if Java is still that much important (is it in 2018 ?) somebody in the community would eventually port it.
No official FM radio app by Jolla Oy or 3rd party (on the official app shop). On 3rd party repos (basically openrepos.net) : - For FM radio, I heard about PirateFM, works on some phones with FM Qualcomm receivers.
But there's the wonderful "OSM Scout Server" (developped by Rinigus on this same forum). [...] This OSM Scout is a local map server. Basically, it's like having your own Google Maps server installed locally on your phone. It can be used by applications such as Poor Maps (simple 2D map displayer), WhoGo Maps (the new best app for maps on Sailfish).
Regarding tethering : - the official interface out of the box only offers Wifi Connection sharing. - By using the network access ("Dev mode" of the USB connector) you could basically do whatever you want. I'm sure there should be some nice user-friendly interface on some repository to help you set it up, but I haven't investigated. I'm more a command line guy, so I basically have 2 approaches : - either I SSH to the phone using the "dynamic proxy" option ("-D" option) of ssh to setup a SOCKS proxy and only set the proxy in a couple of desktop application (e.g.: proxy in Firefox using FoxyProxy for easier switching) to save bandwidth. - or a manually setup NAT forwarding using ip tables. I've never attempted bluetooth networking on Sailfish.
On the official Jolla app shop, you'll find "Documents", an official native document reader for Sailfish. If you install the Android compatibility layer, then you can go crazy with whatever floats your boat. e.g.: The official Aptoid of Sailfish features things like Microsoft Office, Polaris Office, WPS Office, ... but only the Viewer from LibreOffice (?) You can get even more out of other Aptoids, or even from Google Play (if you install Google Services) or Yalp (if you install MicroG, respectively).
Saddly I haven't much experience. Have noticed efforts like Phonehook and scumstopper. But don't know much about it. Info blurb about the first - phonehook - mentions supporting wildcards, and seems to be still used (and htus working ?) in 2018.
Depending on your needs, its pretty much usable as a daily driver. (Still: - check if you have some unusual needs. In your case : check if you can find a decent Office android app to edit while on the go as this is something that you seem to need.