My present connection is the classical Antenna-VCR-Standard TV. (currently I do not have a HDVT yet). I do not have cable in my house and I am not planning to get it.
Currently,
1. I can program my VCR for recording when I am no there.
2. Watch a tv program while recording another one
3. Record the same program as I am watching.

Future (1 month)
I will replace the standard tv with an HDTV.
Can I do the same functions as above?
1. I can program my VCR for recording when I am no there.
I assume I will only record the SD channels since the VCR does not have a digital tuner.
2. Watch a tv program while recording another one.
I assume I can only record SD channels.
3. Record the same program as I am watching.
I assume that I can record HDTV channels.

Any information or confirmation would be appreciated.

You need to mention if you plan to use the TV as a tuner and send that signal to the VCR. Some TVs have a composite (yellow) video out (along with the red/white analogue audio cables) to do that, however, this would typically have to be done "manually". ie, the TV's tuner probably cannot be set for a particular time or date. The antenna connection would need to be split to the TV and to the VCR, obviously.

You could still feed your VCR and record (analogue channel) programmes as before, however, VCRs are very poor signals to feed to an HDTV and you will probably not want to use it much once you see how poorly it looks.

You'll probably want to look into a DVD recorder or an HD recorder option (like an HTPC) as discussed in the OTA or HTPC forum.

The above all assumes that you don't plan to use a service provider like Rogers, BTV or *C as these have integrated HD PVRs available. See the following on Recording HD:

http://www.digitalhome.ca/forum/showthread.php?t=14099

It'd probably be good to know the exact equipment you plan to use and how you plan to use it, rather than us guessing.