If you want to take low ISO photo's indoors, you will need a tripod for the longer exposures, it's just not possible to handhold the camera for them (even with experience
) and instead of pressing the shutter, use the self timer, or if you can get one a cable release and you won't shake the camera and tripod as you take the shot.
As for keeping the camera protected on the beach, keep it in a bag when you are not using it and use a blower after being on the beach, just to blow any sand away. If you have a second lens, be very careful if you need to change lenses on the beach, as you are likely to get sand in the body. If you should get anything on the sensor, there are some tutorials on here for cleaning.
The kit lens although cheap and cheerful it can be a good lens, for a while when I had my 1st DSLR it was the only lens I had and it produced some pin sharp shots.
Hope that helps.