Q3. What is difference in loading balancing with traditional and transactional MOM, RPC and conversations?

Answer:

Message-oriented middleware (MOM) lets a service's consumers physically and temporally decouple from the service providers (see www.webmethods.com and http://www-306.ibm.com/software/integration/wmq/). Communication between service providers and their consumers is asynchronous, and they don't need to be available at the same time because they communicate by sending and receiving messages from designated message queues.
In contrast, Remote Procedure Call (RPC) is a synchronous method of requesting remote service execution. Consumers must suspend service execution until they receive a reply from the provider. (Menasce, 2005)
RPC is a protocol which allows a program running on one host to cause code to be executed on another host without the programmer needing to explicitly the code . RPC is an easy and popular paradigm for implementing the client-server model. An RPC is initiated by the caller (client) sending request message to a remote system (the server) to execute a certain procedure using arguments supplied. A result message is returned to the caller.
Message-Oriented Middleware (MOM), which is a specific class of middleware that supports the exchange of general-purpose messages in a distributed application environment. (Li, Gomez, Tran and Villar, 2008)

In terms of load balancing, MOM transfers messages across servers. If a server fails, then another server takes over for the message' transmission. This is the way MOM implements loading balancing.
On the other hand, RPC does not consider load balancing because Remote Procedure Call (RPC) is a client/serverRemote Procedure Call (RPC) is a protocol that one program can use to request a service from a program located in another computer in a network without having to understand network details. (Li, Gomez, Tran and Villar, 2008)
Put simply, RPC does not consider the access path so RPC does not consider load balancing.

Reference:

1. Menasce Daniel A. (2005). "Scaling the Web MOM vs. RPC: Communication Models for Distributed Applications". IEEE Computer Society in George Mason University, Retrieved from URL - http://cs.gmu.edu/~menasce/papers/IEEE-IC-MOM-RPC-MarchApril2005.pdf
2. Li Zongrui, Gomez Candido, Tran Peter and Villar Jose (2008). "Middleware". Faculty Resources of California State University, Retrieved from URL - http://www.calstatela.edu/faculty/nganesa/College%20Courses/Slide...are%20TPM%20and%20RPC.ppt