Seeking advice on 1800s Warsaw records #poland #records

Barry Clarke

My great-grandmother Molly's 1929 South African death notice states she was born in WARSAW.
Her son, my grandfather Samuel's UK 1921 census states he was born in WARSAW.
Earlier UK censuses state her daughter, Gertrude, was born in Russian Poland. I believe WARSAW.
I suspect too both of Molly's marriages were in WARSAW.

Yet, I have no idea how to verify any of this or where to ask for records: That is the guidance I am seeking.
The limited information I have: 
1. Molly's Polish family name was SZKLARKIEWICZ. Her Hebrew name was RACHEL MALKAH BAT MORDECHAI MATTITYAHU HALEVI. She was born in Warsaw around 1863.
Her anglicized name was MOLLY (MALA?) CLARKE. Her father was MATTHEW (MATEUSZ?). Her mother was ZLATA or SIMILAR. Her brother, MAX (MAKSYMILIAN?), was born
in Jedwabne, Lomza, in 1869.
2. Molly's son, my grandfather, we only ever knew as SAMUEL CLARKE. We don't have Polish or Hebrew names for him. He was born in Warsaw on 22 April 1881.
3. Samuel's father, Molly's first husband, was a STEIGLITZ (or SIMILAR). We don't know his FIRST NAME. We assume Molly and Steiglitz were married in Warsaw as Samuel
was born there. Steiglitz was in the army and died or was killed around the time Samuel was born, around 1881. We know absolutely nothing else about Steiglitz or any family he may have had.
4. Molly emigrated to the UK with baby Samuel, per family sometime between 1881 and 1883. (There are no passenger lists or immigration records in that era from European countries to the UK.) Aboard ship, Molly met JACOB CLARKE, Hebrew name YAAKOV BEN CHAIM ISRAEL, born in Losice, Siedlce. They married (see below). We know MOLLY anglicized SZKLARKIEWICZ to CLARKE because Molly's brother, Max, was known as MAX CLARKE. We know nothing about Jacob or any family of his, and we even wonder if he took the CLARKE name from Molly rather than it being his name too (doubt endogamy as they apparently had not known each other before meeting on the ship.) 
5. Molly and Jacob's UK marriage authorization and certificate show that they married in Dublin in 1890.
6. However, per UK censuses, their daughter, GERTRUDE, was born around 1887 in RUSSIAN POLAND, three years before their UK marriage. My theory is that Molly and Jacob went back for a while to Russian Poland in the mid to latter 1880s, probably had a religious marriage in Warsaw, where Molly gave birth to Gertrude, and when they returned to the UK they married again to have an official UK marriage record. The reason I believe this took place in Warsaw is that I found a Warsaw studio photo of a heavier Molly than I had seen in a later UK photo, and so I believe it was taken around the time of Gertrude's birth. An expert at interpreting old photos dated that Warsaw photo to have been taken around 1887/8, which ties in with that theory. The Majorkiewicz photographic studio at 3 Plac Krasinskich is a somewhat classy address but I don't have a clue as to what that might tell us. Jacob in the UK in the 1890s gave his profession on the marriage certificate as a general dealer and on his naturalization certificate as a draper. 
So, I am wondering if anyone out there has appropriate experience to tell me honestly and realistically what chance there is, AND HOW, to try and locate any Warsaw records relating to any of these births or marriages, or to discover anything more about the family at all. I have tried all the usual ancestry and Jewish genealogy websites.

Thank you,

Barry Clarke
Brit living in Florida. Gmail address: bbclarke98

SZKLARKIEWICZ changed to CLARKE from Warsaw, Jedwabne and the Lomza region
STEIGLITZ or SIMILAR, possibly from Warsaw, died or was killed around 1881

BARNETT supposedly BIENSTOCK OR SIMILAR, from Poland but not known where
NEUMARK changed to NEWMARK from Poznan
LEVINSON changed to BRAHAM from Kalisz
GOODMAN from Poland but not known where
ABRAHAMS from Poland but not known where

Sarah L Meyer  has many Warsaw records from about 1826 to the early 1900's.  1868 is when the records change language.  Prior to 1868 they are in Polish and afterwards in Russian.  The search engine is very good.  You may get a film number for family history library microfilms or there may be a way to "click here to view record".  If you get a film number those films are available in Family History Libraries.
Sarah L Meyer
Georgetown TX
BIRGARDOVSKY, EDELBERG, HITE (CHAIT), PERCHIK Russia (southern Ukraine) and some Latvia or Lithuania