Can the Coinranking website be trusted to show current values accurately by the hour?
if you want accurate price and want it for trading purposes (in other words to make decisions) then you should NOT look at any of the coin-ranking websites no matter if they are accurate or not. instead look at the same exchange where you are trading in.
Should I buy Bitcoin first to be able to trade BCD (Bitcoin Diamond) quickly?
no, they have no connection to each other. BCD is a poor copy of bitcoin.
What is the best brokerage site for BCD in terms of speed of transaction, low commissions, payments in USD when selling, and good customer service?
that should not be the criteria you look in an "exchange" instead you first have to ask for security and trustworthiness. so far none of them offer a good level of security, i'd say Binance is currently better among bad exchanges! (in other words it is bad not the worst).
Any recommendation for good places to learn about best methods for trading, such as forums, books, etc. Thank you to any and all for your help.
unfortunately no.
there are general information about trading that you can gain online from sites such as investopedia.com and some other places but they won't help you much in altcoin trading because altcoins are 90% manipulation (pump and dumps) and 10% having the experience to know how to make profit from them.
