Is there a way to get the work allocation,Team area information of a team member when adding a he/she to the project/Team?

There is (internal) client API to get that information. The API is accessible using the same fundamental API described here: http://rsjazz.wordpress.com/2014/07/22/manage-scheduled-absences-using-the-plainjava-client-libraries/

Some experimental code I am working on:

		final IResourcePlanningClient resourcePlanning = (IResourcePlanningClient) teamRepository
				.getClientLibrary(IResourcePlanningClient.class);
		ResourcePlanningManager resourcePlanningManager = resourcePlanning.getResourcePlanningManager();
		IProcessItemService processItemService = (IProcessItemService) teamRepository
				.getClientLibrary(IProcessItemService.class);

		List processAreasOfUser= processItemService.findProcessAreas(user, null, IProcessClientService.ALL_PROPERTIES , monitor);
		IContributorInfo info = resourcePlanningManager.getContributorInfo(user, true, monitor);

		for (Iterator iterator = processAreasOfUser.iterator(); iterator
				.hasNext();) {
			IProcessArea area = (IProcessArea) iterator.next();
			IDevelopmentLine devLine = processItemService.getDevelopmentLine(area, monitor);
			// as percantage e.g. 20 for 20%
			int workassignment = info.getWorkAssignment(user, area, devLine );
			System.out.println("WorkAssignment: " + area.getName() + " " + devLine.getName() + " : " +  workassignment);
		}

		ItemCollection<iworkresourcedetails> details = info.getWorkDetails(user);
		for (Iterator det = details.iterator(); det
				.hasNext();) {
			IWorkResourceDetails workDetails = (IWorkResourceDetails) det.next();
			printWorkDetail(teamRepository,workDetails);
		}

in the IWorkResourceDetails the owner is the team/project area.Start and end date are either spefific dates or Jan 1 2000 (start) and Jan1 3000 for unspecified. getAssignment() is the percentage and getDevelopment line, the development line.