4 wines? Seems like overkill to me. I'd go with just 2, one red & one white. A crisp white (Sauvignon blanc) with the tuna and a spicy red (Syrah/Shiraz) with the chicken (?).
At a reception, people aren't going to be picky and on top of that 95% of the people aren't going to be knowledgeable enough about wine to distinguish anything extraordinary versus average. If I were you, I would go to your local liquor store and talk with the manager or wine manager... probably best if you go to a store with a knowledgeable wine manager. Ask them what they would recommend considering your dishes and what kind of deal they can give you for a large purchase. They should also be able to help with estimating bottle count as well.
Frankly, you're probably going to get lots and lots of responses that won't really help you here - different wines are available in different parts of the country for far different prices.
No beer or liquor? Definitely get some beer if nothing else, not everyone is a wine drinker and the beer isn't going to be any more expensive than the wine. Good luck!
I agree with SQHD - four wines is overkill for an audience that overall won't care. There are great Aussie Syrah/Sirah/Shiraz for $4-6 a bottle - Yellowtail comes to mind. Same with a Sauvignon Blanc - everybody makes one. If you are real "winers" and want something special; my personal favorite for a white would be an Oregon Gwertzraminer.
Congratulations! May your lives together be happy & prosperous.
Now for the wine. I agree that 4 choices may be a bit much. Having planned several weddings, I can tell you that most folks care more about the available quantity of alcohol rather than the specific quality, at least after the first few glasses. ; )
750 ml bottles can average 4-6 glasses depending on the pour and I think I'd go for either a NZ Sauvignon Blanc (like Nobilo) or a Riesling, either dry or off-dry depending on your guests' preference. For the red, the Syrah/Shiraz option might work, but also think about an earthier Pinot Noir.
Beer, water and sparkling juices are a really good idea as well.
Sparkling pomegranate juice is very popular and I believe would fit in with your menu.
Definitely go down to your locally owned wine shop and discuss your options.
If your lucky enough to have a wine bar/retail shop in your area, you can usually "try before you buy" and that will give you an idea of what's available. Also, ask your caterer if they have any suggestions. Good Luck!