We do not know if that e-bay sale passed Right of first refusal. Nobody would know unless they were the buyer or seller. Generally Hyatt will NOT allow a unit to be sold at less then around .60 cents of the orginal sale vaule. This is for low demand 1300-1400 point weeks. I think a high demand Christmas or Holiday week might need a higher sale to pass ROFR. Hyatt has Windward Point units in Key West they are trying to sell. So, currently The Beach House is a great value. Once Windward is sold out, all bets are off. Hyatt might start using ROFR on many more weeks.
Yes you can use points from more then one week, but you would have 2 MF and Hyatt MF are some of the highest in the industry. So, I would suggest trying to purchase all the points you think you will need with one week. They keep the points in seperate accounts and you would also have to pay for 2 II memberships. But for example, lets say you want to go to Beaver Creek in the winter. You need 2000 points, you would want to use your oldest points first and then if you were short you could pull from the next oldest. Hyatt does have a unique system of points you will want to look at Kal's page. You have to be careful and not let the points get into the LCUP or Limited Club Use Period. You are then limited within a 60 day reservation window to be used only at Hyatt. I had some points fall into this period, Hyatt was very helpful and they did not let the points go unused - they were very helpful in making sure I got the reservation I wanted. So, do not let this scare you - just be aware of the system.