You are right,this gives about 75% correct predictions.
If you dont find it in M.Katakkar's book then im sure i read via some publications of cal astro research.I dont remember exactly the names of the books,but all are in bengali language,as far as i remember.there are very few publications of their own,which are of english or hindi.Only the research papers are in english/bengali.
now to your questions,i would say,that firstly to calculate the year of marriage follow M.Katakkar's way,the 50yrs age division rule.
basically get the idea,and then see the birthchart,navamsha,varshaphalas etc...though for accurate predictions,i think and experienced that palmistry is not enough,u need to jump into vedic astrology.
When the person may/will have child is somewhat related to both husband and wife's success,so u need to look at husband and wife's both active hands,and interpret that in which year both of them are having some promotions/big happiness/or something big expected( which we see thru the rising ones from life line),well again,for accurate predictions,u need to consult birthcharts.In palmistry its diff to predict 100% right in this case too.

my suggestion is that for marriage related and child birth related predictions,refer to birth charts(along with palmistry),that gives somewhat about 4out of 5correct predictions.

in addition to the last post,i would like to mention that,through vedic astrology(mahadashas,antardashas,pratyantar dashas etc) studying fully all the charts(moon,navamsha,varshaphalas),the marriage time predicted is about 99% right in most cases.

And when there are too many lines rising from the marriage line,theres a thumb rule,in 70% cases that indicates 2children.but for accuracy i personally follow birthdatas,not palmistry,because it doesnt give a very accurate prediction.

Could u plz tell me how u determain ages of marriage?
Thanx
Cheers

Tan  

Read the book-> " Palmistry Marriage and Family Welfare" by M.Katakkar
Publisher->UBSPD