The item "1875-1907 Baptisms, First Communions, Confirmations, Marriages Indexes" is probably the original parish register and includes various sacramental records, including marriages and baptisms. This is labeled volume 1 be it marriages or baptisms. Marriages in this volume do not include the place of birth of the couple. It is inconsistent in the inclusion of parents of the bride and groom.
The item "1907-1921 Marriages" generally includes the birthplace of the couple. While many had been baptized in St. Hedwig, there were still a lot of immigrants primarily from the Russian part of Poland (kr. Poland standing for the kingdom of Poland).
The last marriage item, "1922-1930 Marriages" includes a lot of birthdates, but not the place of birth. Are we to infer that those baptisms occurred at St. Hedwig? That's where I'd start. You might get an additional clue if you look up the location of residence given in the record. The number of immigrants who married during this time frame was not as large as before (or at least they're not identified as being foreign born). There were a lot of "corrections to court marriages" which I assume means that a civil marriage was "legitimized" by the church.
The item, "1875-1894 Baptisms" was also labeled as volume 1. It is a book of baptisms for 1875-1894 that copies the baptisms from "1875-1907 Baptisms, First Communions, Confirmations, Marriages Indexes" for the 1875-1894 time period. In preparing the birth index, "1875-1894 Baptisms" was used to prepare the index since the writing is of consistent quality and the pages do not have the wear evident in "1875-1907 Baptisms, First Communions, Confirmations, Marriages Indexes". It did not make sense to spend the time redoing the index although there are small differences. After the index from "1875-1894 Baptisms" was prepared, the index was copied and the pagination from volume 1 was added. Users can check out both records for consistency as they conduct their research. While a transcript is more likely to contain errors, "1875-1894 Baptisms" has fixed some errors or made additions that were left out of the original. So understand that you will most often find two entries for the same person-- one in item 2 ("1875-1894 Baptisms") and one in item 3 ("1875-1907 Baptisms, First Communions, Confirmations, Marriages Indexes"). Since the index is based on item 2, record numbering and other discrepancies between the two volumes is not reflected in the index.
As described above, the item "1894-1902 Baptisms" also copies baptismal records from "1875-1907 Baptisms, First Communions, Confirmations, Marriages Indexes" for the time period of 1894-1898. While "1875-1907 Baptisms, First Communions, Confirmations, Marriages Indexes" ends with 1898 births, item "1894-1902 Baptisms" continues into 1902. I have labeled "1894-1902 Baptisms" as volume 2 because it continues beyond what is covered in the previously described items. The same limitations as above apply.
Volume 1 of death records covers the span of 1886-1918. It seems that pages 41-51 were missing. Records for 1906 are absent and may have been on those pages. It also appeared that half of pages 61 and 62 were missing. Up until 1907, just the name and age of the deceased was given. After that, parents or spouses were usually included in the record.
Volume 2 of death records covers the span of 1918-1936. This volume was not always consistent in providing relationship information. It became more common to include the street address of the deceased, but these were not indexed. One could use these addresses to perhaps connect families if more than one person died at a given address.
Volume 3 of death records covers the span of 1936-1955. This volume continued to include street addresses of the deceased. The volume includes columns for son or daughter, and for spouse. These columns were not always used correctly and so relationships in this volume could be incorrect. Check out the original record before committing to any relationship information in this index. In some instances, however, the relationship was explicitly stated.
Volume 4 of death records covers the span of 1955-1972, volume 5 covers the span of 1973-1992, volume 6 covers the span of 1992-2000. Names are usually spelled out in printed letters making reading easy. The relationships are usually explicitly stated.