Firstly, there are different weights of satin. Go for something nice and lightweight. The simpler cuts do tend to be made from lighter fabrics to add to the simplicity, they also hang better without looking too stiff.
Mermaid (or fishtail) style would be perfect. Go for a 1 piece gown as a 2 piece or separates can cut a figure in half. Also, look at the fitting of the skirt.
For a petite frame, go for a skirt that flares out from mid thigh at the lowest. This will make you look taller and balance your figure. They're also easier to walk in! If you go for a flare which is lower, more towards the knee, this will make you look too 'rounded' and can look stunting.
I would stick to a light satin as they hold their shape better. As chiffon is so light, the cut tends to be more fitted and may not hang right on a petite lady. If you find the satin look is too much, go for something with a delicate lace overlay.
Try some princess line gowns as well. These scoop in at the waist and flare out just above the hip. A gown with a gentle rather than fuller a-line skirt can be very flattering whilst hiding any lumps and bumps. It's great to hear that you want to show off your figure, I've seen many Brides hide behind big dresses and I think it's a shame.
It is unusual and rare but I have seen other colors and I am not talking about off white. The dresses were just like a typical one but dyed to various colors or else just plain made with color material. I have seen pink, black and dark blue. I think there was one or two more but that is about it. It also makes me think of the time when the bride and her mother had matching dresses except the mothers was white and the bride was pink.
I'd recommend going for a one-piece with a 'rushed' waist. Mori Lee have a lovely dress style 5507 - this has a lace-up back for a bit more freedom and the rushed waist brings the waist in and gives you shape.
Try a top and skirt or a separates look dress with a boned bodice. These hold you in all in the right places. Sincerity does a nice one - look on their website and you'll find a couple with the off-the-shoulder sleeves.
However, before you decide on a skirt and blouse(this may be a comfort thing with you), don't rule out a wedding dress. There are some companies out there that do make all kinds of wedding dress to fit almost any size all you would have to do is look. Also, many bridal shops will be having sample sales as well.
Consider an "A"line dress. There are many styles that look good on someone who is petite. I don't know what you consider "overweight", but look on the internet by Signature Plus. This will give you an idea of styles. Depending on at time your wedding is will also dictate what you wear. If it's early in the day, a skirt (long) and blouse would be okay, however, if it's later in the day and reception is after 5pm, you really need something more formal.
Look up a good seamstress. Ask your local fabric store for recommendations and visit with her. They will be able to help you select a style that will look beautiful on you and you'll feel comfortable wearing. You may also be able to spend less by having a dress made for you. If you haven't visited any bridal shops yet, do, if only to try on some dresses and see how the style looks.