Ok I'll try to answer both part 1 and 2 here :
as for the JVM memory parameter with servlet engines : Your servlet engine is executed in a JVM that must allow you to set memory parameters. I don't know about every ServletEngine or ApplicationServers but you can do this with Tomcat or Websphere so I guess it exists everywhere.
As for multiple page sequences, it is simply a fact that the current FOP implementation seems to keep a whole page sequence in memory before it writes it down. So the biggest bage sequence you have, the more heap size you need.
Therefore it can be helpfull to create separate page sequence anytime you can. In your case, it is the worst situation : one long table. You have to start and stop the table each time you want to change page-sequence. Some guy on the list had the same situation to deal with. He manage to have an average number of x row per pages. Then he twisted his XSLT stylesheet to take x rowData (detail element in your case) to build one page sequence containing one table with the x rows and so on.
He has ended with a 97 page-sequence document. This may be a little extreme but it works. The archive pointer I gave you does this trick.
In many case, you have to deal with many tables wich are not always 100 pages long then you can place page-sequences every time you know you can have a page break.
I hope this helps.
Cyril
