1. you can't reRender just list of comboBox, and if you'll try to reRender combo - it will collapsed because of reinitialization of combo component
2. in general you can use your modal objects ... , but combo use
selectItems values or Collection/Array objects from the suggestionValues also for displaying suggestions in the drop/down so if you have appropriate String converter for this purpose you can.
Thank you for reply
Regarding 1) So if i need to have a suggestion action in a combo box with a wild card like search then can you please let me how will I show the combo values when user enter a character in the combo box. Do i need to invoke any java script?