The D7100 is a great camera. You will never outgrow it and because of it's metal build it will serve you for years.
The 18-200mm lens mentioned before is also a good choice overall. Eventually you may invest in a fast prime if you are keen on portraiture.
Although the 18-200 at 5.6 extended to 200mm will shoot very nice portraits also.
As for DWI, i used them quite a bit. Probably spent 20K with them over the last 3 years and they have always been ok.
They did send me a dud lens once, but I got a replacement within a week thru an agent they have here in Sydney.
The dud lens was a Tamron 24-70, but I would still recommend that lens. The replacement works very well and its less than half price of the Canon 24-70.
I also have a Sigma 85mm... and I'm happy with it. I don't think you should worry too much about 3rd party gear. Their new lenses are really good value.