I imagine that seeing "originals" of all of this is next to impossible, but you never know....
The LDS has some family history centres scattered across the world where you can hire in films of parish registers for a fee. They are however trying to put these films online. I was lucky as I had one of these centres within a reasonable distance from me and used to visit it weekly so was able to do most of my research from 'original' registers and not transcripts.
That depends on what film you accessed, some people do not realise that many LDS microfilms are of Bishop's Transcripts rather than the original parish registers.
Though in other cases they were given access to film the parish register.
It is best to always check to see whether it is BTs or PRs.
Cheers
Guy