JomSocial Multiple profiles and some other questions

We still make the Joomla 1.5 version of JFBConnect available, but are no longer developing for it. We do support it and would release a bug-fix or security release, should one become necessary. In general though, we recommend all users to move to Joomla 2.5+ as it's what's supported by Joomla.org and most other 3rd party extensions. If you run into an issue with another 3rd party extension conflicting with JFBConnect, there's likely little support we'd be able to get from that developer, which would limit what help we could provide.

As to your questions:

1. If I use JomSocial with Multiple Profiles, what happens after the users registers on my site through his Facebook? Is he prompted to select his profile type after that?

If you use the "Regular" registration option of JFBConnect, the user will be brought to a mini-registration form. That form has options to show reduced set of fields if you want (no email since it's being imported, no password since it's automatically generated, etc). When JomSocial integration is enabled, one of the fields will be the multiprofile selection field. When the user selects a different profile, the fields from JomSocial on that registration form will change as well.

Additionally, you can use the automatic registration mode of JFBConnect and have all users from Facebook automatically set into a specific multi-profile group.

All profile import abilities work with multiple profiles, so you can import into most of the fields you may have configured for each profile.

2. When I tried your demo, I have seen there notification, that your site has posted update on my FB wall. However, actually nothing appeared on my FB wall. What can be the reason? Is this functionality actually working? (as I want to update user's walls). Again, is it available in Joomla 1.5?

The demo is a little out of date. The Open Graph Actions feature does work. However, the 'read an article' action has been given considerably less weight by Facebook and so usually will not show on a user's Timeline. It can show in that user's friend tickers and other places, but again, it's a lower quality social channel.

Actions like uploading a photo or joining a JomSocial group have a much higher chance of appearing in the Timeline, as well as other 'real' actions instead of passive ones, like 'reading'.

I hope that helps explain,
Alex

We don't have a separate log of features for Joomla 1.5 because we're not actively promoting that version anymore. You can see the last few blog posts for our Joomla 1.5 releases below, which cover the main features you're asking about: Open Graph Actions:
Open Graph Action support added to JFBConnect
Final JFBConnect for Joomla 1.5 announcement
Our JFBConnect roadmap, from the end of 2012
I hope that helps answer your questions,
Alex