As long as your tarantula is not loosing weight and basically looks "normal", don't worry about her. Tarantuals can go for months without eating. Yes, they often stop feeding pre-molt. As for a dirty cage, just wipe any wastes up, pick out dead crickets and whatnot. No need to thoughrly clean tarantua cages. Spiders are not big on periodic re-aranging of their furniture, it stresses them out.