Providence Pentominoes Puzzle By Andrew Bradburn (Jigsaw)

Question

I came across this apparently well known cryptic crossword with a twist but was unable to solve it. I also haven't been able to find a solution anywhere online so I was wondering if anyone here could help me finish it.
Thanks in advance.

So my question is, can anyone solve this for me and explain the bits I was unable to figure out.

Link to download it.

My attempt so far are in the spoiler boxes if you want to try it with or without using my partial solution.

My grid - not fully correct

  *???ER?*
  PURITANS
  LYDIAN??
  A?SUFISM
  GRISLYS?
  UONAORTA
  EFFLUVIA
  *LOFRHP*
 

My answers with my explanations:

Across
1. ??? - no idea
6. PURITANS - anagram of "aunt rips". Fits definition.
8. LYDIA - hidden in "sparkLY DIAmond" Fits definition.
9. SUFISM - end (ultimately) of belieF IS in SUM (total). Fits definition.
11. GRISLY - double meaning - bear & horror. Not sure what 'Reportedly' means here.
15. AORTA - two (articles) A around half of impORT. The heart is a vessel.
16. EFFLUVIA - (backed up iron) EF chimney (FLU) then not really sure on end part. Maybe answer is EFFLUENT but it fitted worse.
17. first letters of (initially) Reaches Home Plate

Down
1. ??? - not sure.
2. FICUS - ficus benjamin is a species of tree, bejamin=$100. Not completely sure this answer is right.
3. ETA - dined is ATE reversed (wrong way)
4. RANI - anagram of IRAN. Not completely sure of this one.
5. ??? - no clue.
6. PLAGUE - capital of Czech PRAGUE with L replaced with R
7. ??? - not idea. Something with SA in.
10. FLOUR - FOUR (beatles number) with meaning of Last. 'Meal' is a synonym of Flour.
12. ROFL - hidden in useR OF Linux.
13. INFO - IN backwards (back) OF. 'Skinny' is synonym of information.
14. STEP - STEPHEN (composer Sondheim) minus HEN (fowl). 'Step' is a type of 'Measure'.
15. ALF - Double definition: Alf Landon & Alf the 80's sitcom.

Problems/Issues with my answers

FICUS and LYDIA don't fit together right. STEP & EFFLUVIA don't find together right. I know one such thing is allowed and a passing comment discussing this puzzle and many others makes me believe that FICUS/LYDIA is right and makes a ¢ symbol which fits.
Also fitting the words I have done into a 3x20 grid doesn't give me a partial message.

Answer 1

The finished grid is:

Rearranged, this becomes:

where you can see "CAPITAL OF RHODE ISLAND" reading across the bottom.

---

The clues you're missing:

1A:

Head of Google = G, provided = IF, file format = GIF

11A:

bear = GRIZZLY, "reportedly" is a homophone indicator, making "horror" (GRISLY)

16A:

"Backed-up iron" = EF, chimneys trapping unknown = FLU(X)ES, outflows = EFFLUXES

1D:

"Appearence" = GUISE, "speaking" is a homophone indicator, making GUYS ("men's")

2D:

Loud = F (as in musical notation), one = I, American = US, "hiding" C: this makes FICUS

5D:

"Repairs" = MENDS; "first off", that is ENDS, which is "remnants"

7D:

"What Wharton confers" = MBAS (as in the degrees). After S.A., this makes SAMBAS.

Answer 2

1 down:

GUYS (defn: men's, sounds like guise=appearance)

7 down:

SAMBAS, multiple Samba(dance), SA+MBA's (from Wharton School)

14 down:

STEP (stepHEN (fowl) Sondheim)

16 across:

EFFLUVES (multiple EFFLUVE=outflow,v EF+FLU+_+ES (chimneys=FLUES, unknown (as in variable? = V)

New Grid:

  *G??ER?*
  PURITANS
  LYDIAN?A
  ASSUFISM
  GRISLYSB
  UONAORTA
  EFFLUVES
  *LOFRHP*