There are some sellers who restrict the number if items a single buyer can buy in a given period of time. Usually they have had problems in the past with 'thrill bidders', mischiefmakers, or lunatics.
It's your postie's job to deliver your mail. No mail. No job.
At worst the postie will leave a slip in your mailbox directing you to go to the nearest PO to pick up your parcel(s), especially if you are not home when she knocks. This is basically a recipient protection measure since constantly having a pile of parcels on your porch or in your mailbox could be tempting to passersby.
Considering phoning the post office and asking them to just hold all of it there to reduce the load
That's called renting a postal box. I think they cost about $30 a month but it's been a few years since I looked into it.