1a) Price and availability can be read in advance and stored or cached on your server, this has the advantage that your server can respond quickly with it's local copy of the data.
1b) Price and availability can be read on demand in real time, this has the advantage of accuracy but may slow down your page. This option is not suitable for multiple properties or situations where many API calls will be needed.
2) The ability to save the resulting booking into Beds24 to adjust availability at all other channels.