All mentioned are those that DO bloom on old wood, so pruning in winter has the potential for removing any flower buds.

There's some mixed opinions on the pruning of these types of hydrangeas - I am of the belief that pruning should be limited to removing deadwood or the occasional rejuvenation pruning. I have never found it necessary to prune to encourage flowering - typically with hydrangeas, pruning does quite the opposite :-) Siting them correctly, choosing them appropriately for your climate and providing them with the best growing conditions is usually all that's needed to enourage growth and flowers.

The attached link to one the better hydrangea sites (IMO) should provide all the info you need. The very first statement is the one that I tend to follow most closely :-)

Here is a link that might be useful: pruning hydrangeas

The only thing I would add is that in colder zones, we don't necessarily know what's dead until June. I'm in Zone 5 and I uncover my hydrangeas May 1 and prune dead stuff out June 1. In Zone 6 you can probably do these things 2 weeks ahead of me.

The link below is a good article on Hydrangea care and pruning.

Here is a link that might be useful: Hydrangea Care and Pruning

I want to cut blooms and stems with leaves for a display inside the house. Is it OK to do this with my new ES and PW Venice/Vienna. When should I stop harvesting the blooms to be sure I get blooms for next year?
These plants have only been in the ground (5 gal) for a few weeks and the blooms are starting to open.