[Toymeister]

To directly address the OP's questions:

Ceramic grills hold up fine. The wood parts (handle, side table) will weather. There are non wood alternatives. Some brand ceramics have weather safe plastic handles and side tables.

Cleaning is not an issue with non BGE brand being slightly more difficult for ash removal. The other brands, most of them, have the ash tray removable through the bottom vent. If you had some grease in the interior you just get the grill to 1,000 degrees and burn it off.

The 13" size is all you need for two people, but I recommend a 18" because there are so many more accessories available on that size.

BGE offers several sizes with the grill diameter being just one variable. Basically, the depth of the grill doesn't matter for most applications.