Congratulations on the acceptance of your paper! Here are my suggestions regarding the publication options offered by the journal:
1) The advantage of open access is that your article will be freely available which would probably improve its chances of being cited. However, you should opt for open access only if you are willing to pay the fee.
2) If you do not wish to pay the fee, you will have to transfer the copyright to the journal. In this case, you are not publishing open access.
3) You can decide whether you should pay a fee to get the figures published in color. However, I would suggest that you pay only if printing figures in grayscale would mean loss of data. For instance, if you have some cell staining image, then you might need to print in color, but if it is a graph, where all the symbols are well-defined, it should not matter if the figure is in color or gray. So in that case, there’s no point in paying the fee.
4) I do not think you really need offprints these days. You can take printouts from the electronic version whenever you want. But in case you want hard copies for special reasons, you can place an order for them on payment of some charges.