Interesting, but I leaves me with a lot of questions:
1. Are there members outside the Philippines? Where and how many? Any in the U.K. For example.
2. Have JWs and the Iglesia ever discussed or acknowledged each other in literature or otherwise?
3. How did they arrive at 1914, with the same WT chronology or another method?
4. When was their best period of growth? JW/BS have been around since nineteenth century, but their growth before 1945 was slow. Is it similar for the Iglesia.
5. What is the proper short way of referring to them? Iglesia?
6. What Bible translation do they use? Since the NWT would probably fit their needs better than mainstream translations.
7. Are they still growing or in decline?
8. Have they received support or persecution from the government?
9. Do they have a Memorial celebration?
10. How does their structure compare with JWs? Elders, circuit overseers, governing body, assemblies, congregations?
11. Do they preach and how?
12. Do they use Jehovah's name or say it is important?
13. Do they teach a paradise?
14. Do they say the "end is near" now or have any prophecy to back it up?
15. Are they creationists? Young earth or old earth?
16. What's thier views on sex and homosexuality?
17. Is there a big community of former members?
18. Any good books on the subject by former members or academics?
19. How many numbers are these questions going to go up to?
20. What prompted your interest in the subject?
Maybe you answered some of these already. I only skimmed the material and these questions occurred to me. I realise the group seems a bit obscure and the answers to these questions would probably take some research. I just lay them down as the sorts of questions that occur to me when reading your information.