Ответ 1
Используя <fmt:formatNumber/>
http://java.sun.com/products/jsp/jstl/1.1/docs/tlddocs/fmt/formatNumber.html
Например:
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<fmt:formatNumber
value="${result.returnValue.contract.balance}"
maxFractionDigits="3"/>