You could only do that with separate E-junkie accounts, so your Goal 1 is not compatible with the others.
That said, posting product listings to an E-junkie Shop is optional. You could just maintain complete separate Web sites of your own for each product line, and paste your E-junkie cart button codes for selected products to their respective sites. However, with a single E-junkie seller account, all payments would have to be sent to the same PayPal Email, show the same Display Name/Email to buyers, and use other common settings from the Manage Your Seller Account section of Seller Admin, so you may be able to get by making those suitably "generic" that they don't relate explicitly to any one product line.