I myself have access to many different consolidator rates so I feel like I should correct a few things OP wrote:
A: First, you won't earn any PQD, as UA don't know how much you paid.
Not true, only if the agent sets the IT command when issueing the eticket, if he issues the ticket the traditional way without the IT command the airline will see exactly how much one paid for the ticket.
The reason why many set the IT command is so passengers can't check via airline websites the "amount of paid" of the ticket and then feel cheated that the agent charged them lets say 100$ on top even thou it was still cheaper than on the metas.
Q: How much does bulk/consolidator fare cost?
A: Those fares usually priced same as published fare for same flight.
might be the case for U.S. domestic flights but not at all for international travel! Of course it depends on the type of contract the consolidator has with the airline but speaking from my perspective, I usually get any international long haul travel tickets cheaper (without any agent discount!) than the metas.
Q: Will I earn 5x/3x bonus if I paid with a premium travel credit card?
A: Usually you get charged by air ticket consolidator instead of airline, so you will earn general travel bonus (i.e 3x with CSR), but not 5x with AMEX PLAT.
Also does not apply to all tickets. It depends on each individual booking, for most of them you can let the airline charge directly via BSP, the minority of the tickets is where the consolidator charges (listed as Travel Agency in the MCC)