I haven't been to many baby showers myself recently and yes things have changed, but here's my opionion...
Unless someone else hosts a shower, I think you should wait until after the baby is born, and have a come meet the baby party. This would work very well as an open house event.
While every child is a blessing and deserves to be celebrated, I'm not a fan of baby showers for 2nd and 3rd babies.
Open house - I've never been to an open house shower. I suppose it could work, but think it would be much more difficult.
Food - If someone is taking time out of their busy schedule to come to your event, and the time and money to purchase you a gift, I think you could give them something much more than cake and a few munchies. You certainly don't need to offer a meal, but a selection of finger foods would be appropriate.
Games - depends on the guests, but I think it's always fun to have one or two silly games.
Congratulations!