Thanks for these questions!
1. No, I want an enclosed environment including tub floor. I understand this ads a little weight, but I'm also using this shelter during bugs and creepy crawler season.
2. Weight is very important, but I'm not an ultra-lite person.
3. Yes and no. Weather here in Northern Virginia can change quickly, with stormy summer downpours. The no is for snow, unless someone with snow gear invites me on a trip ;-)