It means that nothing written in the constitution can be used to cancel amendments to it.
The expansion of railroads created more ways for things such as general goods to be shipped elsewhere to buyers or companies. (Hope this helps a bit, sorry for such a short answer.)
The Crusades is the series of wars between the two groups but if you're looking for a certain one I can further elaborate.
Patriotism, feeling of attachment and commitment to a country, nation, or political community. Patriotism (love of country) and nationalism (loyalty to one's nation) are often taken to be synonymous.