The only way to install Oracle Forms 11g, is to use it's own Fusion Middleware Installer - which generates a "standalone" WebLogic server pre-configured for Oracle forms (and Reports if desired). And there is no way to transfer the Forms Servlet apps to another Basic/Vanilla WebLogic domain.
To install forms, you'll need to download the installer to create the Form's ORACLE_HOME. Then use the Configuration Wizard ($ORACLE_HOME/bin/config.bat/sh) to create the WebLogic Domain and Servers. You can find the installers here: http://www.oracle.com/technetwork/developer-tools/forms/downloads/index.html
A similar process must be followed for BI Publisher, where you download the necessary Binaries then configure a WebLogic Server based on those binaries.
BI Publisher Installation Guides: http://docs.oracle.com/cd/E14571_01/bi.1111/e10539/toc.htm# and http://www.in-oracle.com/Oracle-DataWarehouse-BI/Oracle-Business-Intelligence/OBIEE/BI-Publisher-11g-installation-linux.php
As far as integration is concerned, you can still integrate, regardless of whether BI Publisher and Forms run on the same WebLogic Domain or not. So I wouldn't worry there. If you need help, feel free to check out my link below.