Regular Programming on D*, will it be HD?

If by "regular channels" you mean the standard definition channels they'll still be "regular." They'll stay that way until the broadcaster upgrades to HD. There may be some channels available in HD on DirecTV that Dish still carries in SD, but providers don't upconvert channels.

As for the wiring, leave it. The DirecTV tech may be able to use it.

Most receiver boxes allow you the option for the receiver to either pass-through SD channels at SD resolution, and allow your display to upconvert to HD, or for the receiver to permanently output an HD signal, with your set top box upconverting the SD channels.

You may see an improvement in picture quality if you are moving from composite/s-video interconnection to component or HDMI for even SD content (especially if the source channel is not going through a composite path before uplink) - but SD channels that aren't simulcast in HD will still be limited to SD quality. The extra clarity that displaying SD content on a high quality display offers may also reveal more shortcomings in the SD source (both composite artefacts, if present, and heavy data compression and resolution reduction)