A hub just rebroadcasts all packets arriving at it. I would
be surprised to see a hub supporting full duplex. The broadcast approach used by hubs does not allow full
duplex communications.
If you want full duplex you shoud get a switch. A switch
will store and forward packets to the appropriate
cards. It can read in incoming packet from a full duplex
connection while sending a previously received packet
to the same card.
I have never encountered a card the defaults to full
duplex. Many older cards only support half duplex
as it is the original ethernet model. If you have to
reset the cards, then they have been configured
to full duplex mode at some time in the past.
I use autodetect and only force duplex when I notice
errors on the connection.