1. Remind the guest that all communications need to be kept on Airbnb and that you won't be responding to further text messages.
2. Do not accept her friend request on FB
3. If she asks you a question already covered in your visitor guide - direct her to find the information there
4. Provide her with a link to your local tourist information website
5. I do hope you have quoted her extra for your time to deliver the cake and organise colour co-ordinated decorations
6. Remind the guest to read through your listing and guidebook and IF the information she wants related to your listing isn't in there she can message you on Airbnb. For any other information she should look on the local tourist board site/use Google.
In terms of the specific requests, I would let her know you normally charge £300 a day for concierge services including researching and identifying suppliers, picking up and delivering items, responding to guest requests etc but don't have capacity to provide these services currently.
Suggest she uses Lonely Planet/local tourist board website to find out about local amenities and Google to find local suppliers for her celebrations.