In the Bathroom
Bathing baby twins is no different than singletons except you have to do everything twice.
Bathing baby twins at the same time is not
practical or even safe. You are better off bathing them separately
one after the other. It would be very helpful to wait until you have
help in the house to bath your babies. 
Never ever leave your babies or toddlers in the bath tub unattended.
Some people use their kitchen sink to bath their babies, but baby bath tubs are very practical and useful.
For potty training you can start at anytime you feel your toddlers are ready. However, it may be easier to wait until they are about 2 - 2.5. The plus side of training them earlier though is cutting on the cost of diapers.
Click on the images for additional information.
Try keeping toddlers occupied when you bath them:
If you plan to travel with your toddlers or even go out to the grandma's, you may want to consider this travel Potty: