We are planning to be there. Do you know what else is there to see apart from the house ? Can we roam in the Garden ? How much time would it take to cover this place?

You can also not worry about the time & just absorb the surroundings.

About 15 minutes really

You can roam the garden and we had a tour of the house explaining the architecture and the use of many of the items in the house. Not too far from there is a great resteraunt and market. It is called Maido - very clean and organized.

They have a large pond filled with koi that you can feed. Plus it is near the conservatory/garden center that's just a 19 minute walk. There are some interesting statues that you can see, plus it is near the Philly zoo.

Yes you can roam around, and 20-30 minutes tops.