Those are some very good questions. I know that around the same age that your baby is, I went in the opposite direction. (from outside potty to pee pads) Trust me it can be done! As far as how to go about it.... well... I'm a little lost there. Kaji came pre-trained to use the potty outside so I have no idea how to go about it.
I'm a big anti crating person. While I completely understand the concept, I don't like the idea of it, but that's just me. Does she go potty immediately after you come home?
What I would do in your shoes is I wouldn't change how I'm keeping her during the day. She's use to it and she doesn't even use the pee pad when you're gone anyway. As soon as you wake up in the mornings, take her out. Use whatever command you use inside to let her know it's potty time (I use "go pee pee"). Give her a chance to sniff a bit and make sure she potties. Go back inside, do your regular morning ritual, then right before you leave, take her out again. When you leave, leave her in the kitchen like you usually do, and at first, leave a pee pad for her. As soon as you get back home, immediately take her out, then again before bed. Give her as many opportunities as you can for her to succeed and over time she will get it. It's hard to go from what they know to a new system. Kaji still gets excited when he's allowed to potty outside. He actually gets giddy.
He's really good with the pee pad now, but I know he secretly would rather pee on a tree.
