Hi,
1. It depends on your configuration for the requested field during the registration.
Please provide details about your HikaShop login/registration settings.
2. Yes, that is totally logical and it's also a security measure.
At the moment when you have an account (email + password) you need to identify yourself with that password.
Otherwise you could create orders for an account you do not have and possibly access to elements you should not.
Now by changing a little the translations ; you can indicate to the user that he already have an account with that email and that he should login with.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.