If you have placed the image in Muse using File > Place and then scaled the image down in Muse while editing, then Muse publishes/exports the scaled down/optimized image in final output. When using as a Fill, the output size depends on the Fitting option you setup in the Fill options.
As for the contact form email, you would need to specify the email address for each form individually. There is no workflow to edit the same for multiple forms at a time.
Cheers,
Vikas