First I want to congratulate you for posting information that is supported by sources (unlike too many who keep on perpetuating errors).In this post, you write:
"There is a question concerning the year that Jean and Anne were married. Most records show that they were married on 17 Nov 1635. If that had been the case they would have married about a month after their son Louis was born and Anne Martin would have been 6 months pregnant before Jean left France. I am inclined to go along with PRDH and say that a wedding date of 17 Nov 1635 is an error and that they were married in 1634 or someone used the old calendar. (When I first started my research many dates showed up as 1634/35 for the old and new calendar.) When their son Louis was baptized by Father Lallemant on 25 Oct 1635 the PRDH report # 57108 stated that Jean and Anne (the parents of Louis) were spouses. I have not seen the original birth records."
The birth record ofLouis Coste is available on-line through labs.familysearch.org.Here is what it says: Le 25 octobre de l'an 1635 fut baptisé à Québec Louis fils de Jean Coste et Anne Martin par le père Lallemant M Giffard et Louise Couillard, parrain marraine.
Therefore there is not the phrase "né du légitime mariage de"but it is not written "fils naturel" either. Of course we are working with reconstituted records after the fire of 1640.However, since all involved were still around when it was done, it is probably quite accurate. The date of birth of Louis is correct because it fits with his age of 30 in the 1667 census (his birthday in the fall, after the census).
As for the origins of Jean and Anne, we seem to be facing a lot of "unknown" quite unusual for a country otherwise obsessed with record keeping.My impression is that we are here facing what I will call the "Huguenot factor".The king had decreed that Huguenots would not be allowed in New France - yet known Huguenots like Abraham Martin, Nicolas Marsolet and Emery De Caen were certainly allowed. The rule was that they were to keep a low profile and openly behave like catholics.I therefore think that Jean Coste was probably of Huguenot origin.Although he is buried in the church and recognized as a pioneer, his death certificate is silent about receiving the last sacraments - it just says he died at home... The problem is of course that protestant church records are hard to find, especially when we don't even know the area.There were some Huguenots with the surname Coste in Ardèche for example, with a few Jean born around that time - but there are probably many other parishes. If his father's name was indeed Abraham, then for sure he would have been a Huguenot as well. (Anynone knowing where the Abraham Coste- Françoise Geneviève Loisel idea came from, please show you source!). As for Martin, we know of course that many of them were Huguenots.