Hi sapphire
most banquet venues require the min table.it is like economic of scales. more tables, more bargaining power. but no harm asking. call the wedding consultant. they would love to answer ur queries. if they dun, they are losing biz to other worthy compeititors.
for dinner, the consumption of wine may be high, depending who u invite. most working adults are appreciating wine, so they may have at least 2-3 glasses of wine.