Please post your question to everyone and start new threads for each question as it will be easier for anyone to help on one points.

>How can I create a Read - only object property?
You need to have a public "property get" without (or with a private) a "property let".

>What is the difference between COMMAND object and RECORDSET object?
Command contains query (SELECT, INSERT, UPDATE, DELETE)
Recordset contains the result of a SELECT query.

>When can I use a ActiveXDLL in place of ActiveX exe?
When your component will be executed locally and in the same process as of your application.