Binance Fees and Prices

Hi guys, I am relateively new to Binance and there are some fee-related aspects that I'm not completely sure about, although doing my best looking for explanations on Binance website.
Hopefully you can help me clarify them.

1. Does Binance apply a bid-ask spread? If so, where can I find them for each crypto?
2. Why am I shown different prices depending on whether I am buying crypto with Credit/Debit Card, with Cash Balance, or via Spot order?
3. Why are the prices shown by Binance generally higher than the ones from other exchanges (Coinbase, FTX, ...)?
4. I registered via a referral link and have turned on the "use BNB deduction" option. This should grant me a maker/taker fee of 0.06% on Spot trading, as shown here. From my order history I can however see that a 0.075% fee is applied instead, as if I was not benefiting from the referral link discount, just the BNB deduction. Why could that be?

Thank you in advance for all your answers!