Upgrade BO DS from 4.0 SP 2 to 4.2 SP2

Hi All,

I am planning to do a Upgrade of BOBJ Data Services from 4.0 SP 2 to 4.2 SP2. I have few doubts as follows...

1. Do we need to stop any development before we start the upgrade in Development environment?

2. Do we need to take any backup of files, configuration? Will anything gets overwritten, like connections, etc?

3. Do we need to update IPS first? Do we need to update TOMCAT server?

4. What is the best process for upgrading, is it upgrade the existing Instance or uninstall and upgrade and then migrate the data?

5. Any issues you found in the process of upgrading?

Thanks

Krishna