Records in Iowa

I am just starting this process which involves collecting records.

I can find birth and marriage records in Luxembourg from the 1830's and 1840's which is kind of cool.

My problems start in Iowa.

My 2 times great grandmother was born in 1870 and Iowa does not keep birth records that far back.  I have her listed in census records but was also going to try for Baptismal records from the local Catholic Church.  Is that hard to do?

Then when my great great grandmother got married they misspelled her name Hentges as Hinkley on the wedding certificate as well as that of her father -- they did list her mother's maiden name of Phillips correctly.  Is this an issue?  (They were married by a Justice of the Peace so no church records to check.)

Finally, when my grandmother was born in 1892 (about 4 months "prematurely") they did not list her name at all on the record and again listed her mother's maiden name as Hinkley not Hentges.  Is this a problem?

Any thoughts you might have on where to pull alternative records would be appreciated.

Thanks,

Bob