Re: First day back questions...
1. Leave 1-1.5 oz per hour away, so assuming no commute time, 12-18 oz for first shift. Yes, from freezer stash.
2. Since she's taking small amounts anyway, I would make these in 2-3 oz bottles - maybe 3 3oz and then a bunch of 1-2 oz to top her off when she wants a little more?
3. Hm. Thurs to Mon is 4 days, and that's definitely safe but also slightly on the older side. The other option is to freeze Thurs' milk immediately, and rotate out your freezer stash. Both letting milk sit for 4 days and freezing it diminishes some of its awesomeness, but I don't know the relative amounts. I'd say this one's kind of a tossup. But if you're pumping more than 12-18 oz, make sure you freeze the overage right away.
Good luck!! You can do this.
Nursing, pumping, cloth-diapering, babywearing, working professor mama with the awesomest SAHD ever.