How does Bitpay.com getting transactions info as its open source? How does Bitpay.com wallet getting transactions info and listing unspents?

Are they connecting to Electrum servers peers or are they connecting to their servers?
You can check your transaction's confirmation status and other payment details on any blockchain explorer (like BitPay's block explorer Insight). Look up your transaction using your transaction ID or the sending or receiving bitcoin addresses, which can all be found in your bitcoin wallet that sent the payment. For your transaction to be considered fully confirmed by most BitPay merchants, your transaction will need to have six confirmations.

More info: https://insight.bitpay.com/