i would get a small piece of plexi glass and silicone it over the holes. that or buy small bulk head plugs, i think that will make it uneven on the bottom tho. sand i would go w/ some black tahitian moon sand. are you gettin the ornate uromastyx??? get a blue and a lime green one!!! the crack on the front i would just get some silicone and try to force it into the cracks and fill it in on from and back as best you can. i don't think you have much to worry about, it isn't going to be holding water anymore, you should be golden, i used a cracked 55g for my leopard gecko setup a couple years ago. works great. i made my own screen top w/ openings for feeding and made it sturdy enough i could just set the heat lamps on top of the screen rather than hang them,