I am attempting to buy a new camera

[Bebulamar]

You asked a question that can not be answered. Which camera should I buy can really be answered by the person who is going to buy it. Of course I do have sympathy for beginner who doesn't know anything about cameras. But after 4 years of experience and now you know enough to become a professional there is no reason you can't make your own decision.

 

[dennybeall]

The 18-140 lens is good and will give you the range you need for what you're looking to do. If you can afford the D7100 then go for it. The D5300 and the D7100 have basically the same sensor system while the D7100 has a couple features that can be useful for a pro.(as mentioned earlier - dual cards, etc)
Keep in mind you also need tripods, data cards, flash units, reflectors, advertising, etc., etc. so put those costs in that budget.
The D5300 does require a lens with the focus motor built in, the -S in the lens description. So many older lenses don't auto focus on it. (No problem if you do manual focus most of the time)
I use an older 300mm lens and manual focus and it works fine.

(Not sure why all these folks are in attack mode IN THE BEGINNERS FORUM.)