Eggs are pretty darn durable. As long as they aren't laid/left in a water dish(drowned) or directly on the heat source(fried), they're usually fine for days. You could simply throw some lightly dampened sphagnum moss on them and let the female incubate maternally - until you get everything set up for artificial or even letting her take the clutch full term. Ventilation in tubs comes down to personal preference. I drill a few small holes in my tubs for air exchange and find it helps cut down on mold a bit. If you use a lot of ventilation, you'll probably have to add water to your medium at some point. If you go substrateless, you probably won't want holes or you'll struggle to keep humidity high. I'm a vermiculite guy though so my eggs get partially buried.