Patching Doubt :

c and g drivers BOTH will go on all those nodes which have APPL_TOP present on them.
So now it depends on our configuration of the "web" node.
If our Web node is a pure web server with only IAS_ORACLE_HOME on it then we donot apply "Apps" patches(c,d or g) on them,we will apply only "oracle" patches there.So neither c or g go should go on a pure Web node.

And if our Web node is also handling a bit of forms(which is normally the case) i.e. if it contains any plls etc.. then BOTH c & g drivers will be applied.


QUESTIONS:
1. What is wdbsvr.app file used for? What's full path of this file? What's significance of this file ?

Database connection information, IAS_ORACLE_HOME/Apache/modplsql/conf

2. adident utility is used for what ?
to find file version

3. How can you license a product after installation ?
adlicmgr.sh or via OAM (Oracle Application Manager)

4. What are main configuration files in Web Server (Apache) ?
httpd.conf, jserv.conf, jserv.properties, zone.properties....

5. How to check if Apps 11i System is Autoconfig enabled ?
Check in any configuration file and if on top of file it is written that created by autoconfig

6. How to check if Oracle Apps 11i System is Rapid Clone enabled ?
If rapid clone patches are applied

7. What is the difference between apps listener & web listener ?
Apps listener are FNDFS and FNDSM listener and web listener is for web requests (HTTP/HTTPS)

8. What is difference between adpatch & opatch ? Can you use both adpatch & opatch in Apps ?
adpatch is used for applying apps patch
opatch is used for applying database patch

Yes both are used in apps , adpatch for apps patch and opatch for database patch

Significance of _ALL tables
_all tables store data for all organizations if you have multi-org enabled