hey 'python , the 1st slide course is a short course designed as an introduction to slide for people want to add a bit of slide to their playing , its in standard tuning.I have not looked at it but I think Rue has a copy of it ... I had not played for 20 + yrs but I did play a bit of slide , so all I needed really to get back into it was to throw a slide back on my finger !
Having said that , the 1st book shows some basic techniques for sliding & I think Griff talks about finding a slide that fits etc
A lot of this can also be found in the new slide course , exercises , licks , talking about slides , where to wear it ( but that is personal preferance no matter what anyone tells you ) songs too ...and this is done in standard tuning , open D & open G.
So I think you could go straight to the new slide course without any major drama's.