Creating custom installer by using WiX tool set

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C#

Hello,
I need your suggestion in creating customized installer which will give user options to install application locally on user machine or on network.
During the installation I need to read values from external .config values and write to external .config files. Is it possible to pass values to .msi installer package from external file setting (without passing them from command line) and also is it possible during installation to override external .config values?
Also I will appreciate if you could suggest what will be the best approach for building custom installer with above options?
Thanks in advance!!

Lora