Is it possible to use my Poloniex coin address to accept payment via Paybear? It's kinda difficult for me to keep data on several tokens so I would prefer a single log in via exchange.
Customers can pay from any wallet, exchange or even a smart contract. Although not recommended, you can also use your exchange address for payouts, provided that its reusable. They have this info and all other potential questions in their faq
https://help.paybear.io/frequently-asked-questions.