Hi,
I have worked on numerous installer system including Wix based MSI Installers.
Also, as you have 10 InnoSetup pascal scripts transforming line by line would be a tedious job. If you have the functional spec, then it would be easy.
Also, for your Req#2, installer can be made silent and hidden from desktop and program features list.
Please have a discussion to further discuss more on the options and we will take it forward.
Thanks,
Kamleshwar.