Stan,
I think that the attraction of VHS videos is that they can be transferred to DVD or converted to a digital video format that you can play on your PC, Tablet or Phone.
Any decent tar and glue remover will do the job.
I use Neilson Chemical stuff for the Trade which I buy in 5lts.
Google is your friend;
https://www.google.co.uk/search?source=hp&ei=ua_8XJbsL-aV1fAP1MyawAk&q=tar+and+glue+remover+for+cars&oq=tar+and+glue+remover&gs_l=psy-ab.1.2.0l10.2521.8253..11434...0.0..0.92.1427.20......0....1..gws-wiz.....0..0i131j0i10.689IExg0Ilc
You are correct, as there is a plate on top of the gearbox which stops you accidentally selecting reverse.
The plate will require adjustment to make reverse selection easier and it is only a 5 minute job..
The CD009 transmission will bolt straight onto your DE engine.
Unfortunately the above are not compatible with an HR engine.
Regarding the slaves, a CSC delete kit is available.