Canon 7d information?

I currently use a canon HD camcorder (hv series). I also use a nikon d70s for photos. I was looking into these HD video DSLRs, and couldn't help but think this may be a great way to knock out 2 birds with one stone.
-are these cameras a valid replacement?
-in using SLRs, you adjust the focus, aperture, and shutter speed manually (atleast you should). When shooting in video, is there any way to tell if the video I'm taking is too bright/too dark besides using the light meter?
-can you adjust shutter speed in video mode?
-is there continuous focus on these models?
-is there a limit to how long your clips can be?
essentially I'm looking to replace most of my equipment with one of these things. Not necessarily the 7d, too pricey for me. I was looking into the nikon D series and the Canon T2i. I'm worried I won't like the DSLR though.
so really I guess i'm asking what the true cons are of these designs.

You are better off with both a still and video camera. The video features on a DSLR are a nice feature and they do a pretty good job but they are not a replacement for a true video camera. Currently there's only one DSLR that has auto focus in the video mode (Nikon D3100) though not for long.

You already have gotten it right. Why change it? Two separate cameras for two different applications. The video on a dSLR is just a feature. Don't expect the digital still camera to behave like a digital video camera.

If you just want a video DSLR. Get the D3100. Or the D7000.

I would consider Canon EOS 7D 18 MP CMOS Digital SLR Camera
* 18.0-megapixel CMOS Sensor and Dual DIGIC 4 Image Processors for high image quality and speed
* Advanced HD movie mode with manual exposure control and selectable frame rates
* Intelligent Viewfinder with 100 percent field of view; 19-point,
* All cross-type AF system equipped with dual diagonal cross-type sensors
* Capture images to CF Card Type I and II, UDMA-compliant CF cards
http://www.amazon.com/...002NEGTU6/

If you like the 7d but not the price, then go with the t2i. A lot of people complain about auto focus, but i prefer to shoot everything manual.