Hi, welcome to this forum
wondering if there is a way to create rolling credits on a slide?
There's one template under Subtitles that should work great for this purpose. It's more like Starwars, though, due to 3D rotation used, but you can edit it so it's more like classic rolling credits. Just write here if you need the steps on doing this.
can you add 'title clips anywhere in the slideshow or will they only sit at start/end?
Sure, you can move title clips anywhere you need - with drag & drop, or copy & paste (the hot keys are Ctrl + X, Ctrl + V)
and one final question... If I want to use the Slideshow in 5 minutes.. is it possible to create multiple slide shows and link them so they play continuously?
You can't join the projects, but you can convert them to videos and then join the videos.