Large releases (7.x) are generally feature releases; and none are slated as far as I know (seeing as 8.x is being worked on). Instead, at this point, bugfix releases (7.5.x) should be all that is released.
AS for what's been changed, you'll need to go look at the changelog forum, as this is what it's for, to tell you what's changed in each release.
As for changes to the layout (templates) it'd be included in the changelog, however any modifications to the code are completely unsupported by the UBB and should instead be directed at the company who preforms your forum maintenance.
