Yes, but as others have said you might want to coordinate with the staff for formal photo shoots.
Yes
Of course!
Yes what to the e above said
You will need to contact the garden to see what the rates would be.
If it's a small event (two or three people), I don't think they'll mind, you've paid to get in. If you plan on having a large crew (everyone will still be paying) you may want to call to reserve.
The quick answer is yes. However, check with the administrative office for needed permissions etc for professional or commercial photoshoots and to reserve time slot(s).
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