Hello,
1/ We found that you have enabled Email builder -> https://prnt.sc/Ao18FVpmGRr3 which may cause those issues you asked about ‘If cx is creating account at the time of checkout we will need to send two emails’ – so, please, disable that switcher and recheck from your side. Also if the issue is still there, check how it works with the default StoreFront woocommerce theme.
Check your contact form settings and set correct values -> https://prnt.sc/eDAWiHM_ZrEu
Also, you can use antispam plugin, for example – https://wordpress.org/plugins/wp-contact-form-7-spam-blocker/
Regards