Based on the Digital Photography Review ("dpreview.com") website, no. See:
http://www.dpreview.com/news/0801/08012403canoneos450d.asp
yes by downloading EOS MOVIE RECORD
no
No it does not. These Canon EOS cameras have video mode: EOS-1D Mark IV, 5D Mark II, 7D, Rebel T1i, and Rebel T2i. (as of June 2010)
In terms of quality, the ranking of Canon cameras from lowest to highest among the models you mentioned is: Canon EOS Rebel T7, Canon EOS 90D, Canon EOS 5D Mark IV, and Canon EOS-1D X Mark III.
Canon eos rebel t3 slr is a better camera compared to canon eos rebel t2i
Absolutely yes. Canon EOS 450D has the same mount as Canon EOS 400D, wich is EF and EF-S.
Some Canon BP-511 compatible cameras available in the market include the Canon EOS 5D, Canon EOS 20D, Canon EOS 30D, and Canon EOS 40D.
Yes, with the right adapter.
The latest models in the Canon Rebel series are the Canon EOS Rebel T8i, Canon EOS Rebel T7i, and Canon EOS Rebel T6.
You cannot record video/sound with Canon EOS 20D. It takes only photos with RAW/jpg output format.
The Canon EOS 500D is made in Taiwan.
There are plenty of places that has the canon eos online. One place that has this camera available is at http://www.pricegrabber.com/canon+eos+d2000/products.html