Disneyflorists can easily get baskets delivered to the room. Not sure if you can specify a time in the day or not.
However, one thing to keep in mind while planning, if there is any note anywhere on your reservations,
a CM may accidentally spill the beans. This would apply to a basket delivery as well. If you are going to be at the parks all day long, then it shouldn't be a problem. But if you are possibly going to the room to change or something else, and they delivered it early it would ruin the surprise. Just something to keep in the back of your mind.
Also, going back to your original question it partially depends on when you are planning to do it. You can book a private session with a photopass photographer at the Poly. I believe you get about half an hour for like $50 which includes some prints. CD is available, but for an extra cost. But they only do this from like 8-5. So if you were planning on fireworks or sunset, usually a no-go. But you should be able to book a session with them during the day, and then surprise her with the question. Most PP will keep on shooting during that moment. BUT, remember that the PP are not all professionals, so the photos may be better if you go with the professional package through the wedding/events group. You can get more info on the private photopass sessions at
http://www.stitchkingdom.com/disneysphotopass/
