I have so many questions for you:
#1: Are you planning on doing professional wedding photography, or are you planning on taking this camera to a wedding? A $1000 budget is very very very low for a professional wedding photographer.
#2: Is this a training camera, to learn how to shoot before you get a better one? Or do you intend to go straight to charging money for your services?
#3: Are you familiar with photography editing software (Adobe Lightroom, and Photoshop)? Are you familiar with editing RAW files?
Here are a few answers to your questions:
#1: Any modern camera will take photos that are just as clear as the next camera. It comes down to how you are shooting, and what lens you have attached to the camera. Your first choice would be full frame vs. crop sensor. With a budget of $1000, it looks like that narrows things down to crop. If I were doing professional wedding work, I would want the features and flexibility of a full frame camera for many reasons. With that said, the D7100 or even D7000 are very capable cameras & could be used for professional wedding work.
#2: The D3xxx / D5xxx cameras are not going to cut it for professional wedding photography. That means you're looking at a D7000, or D7100. You can find the D7100 for about $800 new, and for about $1090 paired with an 18-140mm VR lens. You'd be better off getting a D7000 for $500 or thereabouts, and getting a 35mm 1.8G and 50mm 1.8G... and that still isn't great.
My advice:
#1: Please respond with some information about your experience with photography, and what you intend to do with the gear (what time-frames you are thinking of). It is potentially unrealistic to pick up $1000 worth of gear and start shooting weddings. Experience is going to be an issue. Software on the computer is going to be an issue. And the lack of gear is going to be an issue. I would consider it potentially irresponsible to be the sole photographer at a wedding if you don't have a minimum of 2 camera bodies, alongside some other gear. The reason: The wedding can't be done over, and if your camera craps out on you, that's game over. In addition, you would need at least 1 extra battery, and that would be cutting things close.
#2: Unless if you're really doing a major budget wedding (getting paid pennies because the bride/groom just want really basic and cheap photos), then you should have an array of equipment:
- At least one flash.
- At least two camera bodies.
- At least one portraiture lens.
- At least one fast normal range prime lens, or f2.8 normal range zoom lens.
- Some lens to reach a 24mm full frame field of view (an f2.8 normal range zoom lens could do this).
I wouldn't shoot a wedding without the following:
- Two D750 bodies.
- One ultrawide lens
- One 24-70 f2.8
- One 70-200 f2.8
- Some primes (probably at least 2), some combination of the 28mm, 35mm, 50mm, and 85mm f1.8 lenses
- Some way to do macro
- One flash minimum, plus flash accessories (diffusor, reflector, flash stand, etc)
- Additional necessary accessories (bags, batteries, extra storage cards, wireless trigger, tripod)
- A second photographer.