a. Yes.
b. Mostly. The only thing you don't have is the ability to jump into a SPHA without a bit of additional TK (see answer below regarding ATPLs)
c. No.
d. No.
e. No.
I note you are continuing with etc 14 ATPL TK exams. There's a bit of a question over the privileges of a CB-IR graduate who holds valid ATPL TK; does the SPHA limitation still apply? I have sought guidance from the CAA regarding this and they say (not in writing) that a CB-IR with ATPL TK credits is exactly the same as a standalone IR. That makes sense as the CB-IR is best described as an alternative mechanism for gaining an IR and the flight test, pass standards etc are all exactly the same. Furthermore, anyone undergoing SPHA training will have to undertake a type rating course (approved course at an ATO etc) so the SPHA TK limitation could easily be swept-up in the ATO course.