Move to Canada, Was on H-1b Visa and Concerned Using Us Bank Accounts for Business

[AYUSHMANN]

I moved from USA to Canada in 08/2016. I live in Toronto now with my parents.I was in USA on H-1B visa from 10/09 to 8/16. My U.S bank accounts are still active.I'm going to start an E-commerce business on Amazon USA website and will be using my US chequing accounts to get my profits pay from Amazon.My queries:
(1) Will USCIS or IRS raise any concern on why my bank accounts are showing big transactions every month if I am not staying in U.S.A?
(2) To avoid any red flags from USCIS, is there any safe limit on the amount of US dollars I can transfer every month from my US bank to CA bank?
(3)I'm planning to raise money through my friends for my Amazon business.Is there any limit on how much money I'n take from them legally via wire transfer in USA since I don't live in USA?
(4) Is it ok if I never close my bank accounts I've in USA?