I recommend the 450D, especially seeing as you are just beginning. Two good lens choices would be this one,
Canon | Zoom Wide Angle-Telephoto EF 28-105mm | 6469A005 | B&H because of it's aperture range and USM focusing capabilities. Since you shoot wedding fashion and portrait, a telephoto lens would greatly benefit you when you need to get in close on the subject, without getting too close like you would have to with a wide angle. This lens is also 28-105, a great wide-telephoto zoom area, which will allow you to not need to carry, say, 3 lenses around that are within this range.
Canon | 100-300mm f/4.5-5.6 USM Autofocus Lens | 2565A003 | B&H is another great choice, particularly because of the focal length.
Oh, and always, that is ALWAYS, stay away from third party lenses.
Always.
You've seriously had your camera for what, a month?
For wedding photography, full frame is always better. Can it be done without? Yes of course it can. It is being done with crop sensor cameras. Full frame cameras control noise better at higher ISO's due to the size of the pixels on the sensor. The problem is, the sensor is expensive to produce and that makes the cameras expensive. Right now, the cheapest full frame camera can be found for about $1300, and that's a
used Canon 5D.
A 40D would be much better than the 450D. You can find them used for about $600 and that's a killer deal on that camera. Up to 6.5fps, metal body, faster AF, much better controls.
For the money & features, it's definitely best to skip entry level Canons unless you must absolutely have one.
Wedding photography....lenses? Fast aperture. 16-35 f/2.8, 24-70 f/2.8, 70-200 f/2.8IS, 50 f/1.8, 85 f/1.8, etc... Range doesn't matter as much as speed when shooting weddings.
Portrait and fashion/glamour? You could get a Canon XTI, Nikon D40, Pentax K100D, Olympus Evolt 510, or Sony a300. It doesn't matter. What matters is ligthing. Portraiture and fashion/glamout photography depend heavily on lighting. You forgot to mention that, huh? A set of strobes would possibly be the most important thing to worry about there, not the camera or equipment.
Third party lenses rock. If you don't have the cash to drop on expensive pro glass by the manufacture that makes your camera, third party lenses are an very good alternative.
Sigma 10-20
Sigma 70-200
Sigma 150-500
Tamron 24-70 f/2.8
Those are some I know off the top of my head that can compete with first party lenses for a fraction of the price.
And always, ALWAYS get a fifth opinion on the internet, you don't know whether the person dishing out advice has 2 months or 2 decades of experience.
Edit: And I forgot, the most important thing is knowledge and patience. If this is going to be a serious hobby it can get expensive and time consuming. There's ways around everything though. You don't have to jump in with a $5000 camera kit and just remember to keep learning as there's always something out there that can help improve your photos and it's not always going to be a new lens or a new camera.
