OK, to address a couple of your questions:
I am also a woman on the larger side, so I understand your concern about not wanting to invest in a lot of clothing that won't fit in a few months. But you do want to be comfortable during this journey, as well. Now- I don't have any stores in my area that I can just walk into and buy quality cycling clothing. I really like REI online for a variety of things, and their membership is great, so perhaps if you have a brick-and-mortar in your area, give that a try. I've bought these:
Performance Bibs, which are great as I have been increasing my mileage, and I don't think I will be going back to regular shorts (even with the padding) again. I went to Target to get a few technical wicking T-shirts instead of spending the $ on jerseys just yet. I live in the Southeast and I have found
This to be great for under my helmet.
Sorry, I don't ride in skirts so I can't offer any help with that.
But good luck and happy riding!