does SH404SF provide special support for Jomsocial 4.7.7?
If talking about URL structure, we do have a panel providing options for URLs for JomSocial. I cannot say whether it supports JomSocial 4.7.7 specifically. We have stopped supporting JomSocial officially a while ago and this panel is only a convenience at this point. A social network-like extension is not the most well-suited for building URLs and storing them in the database as:
- they produce a lot of URLs
- most of the content is not meant for search engines
which is why we do not promote support for JomSocial anymore.
Is it correct that SH404SEF can only work properly with J-BusinessDirectory if a special addon for J-BusinessDirectory (JBD-sh404SEF) has been purchased previously?
I have no such information. JBusiness directory is like any other Joomla extension, we do not "support it". We build URLs for it by using its router.php file, with a couple of generic options dealing with how the URL produced by JBD router.php file are used and stored. We only provide actual URL support for Joomla native content, Virtuemart, Community Builder and Kunena, altough we plan on deprecating CB and Kunena support for the same reasons as JomSocial. CB and Kunena are much more common which is why they are still there.
If there exists such thing as a "JBD-sh404SEF" plugin, paid or not, I'm not aware of it and you'll have to talk to its developers for more information. We have many JBD + sh404SEF users but I'm not aware they are using a dedicated JBD-sh404SEF plugin. I don't see why that would be needed althoug of course if well done, it would be very useful.
Please not that aside from URL construcion options and configuration, all other sh404SEF features will work normally with any Joomla extensions, including the ones mentioned throughout this message.