I'd start by test riding the bikes you've found, and perhaps trying similar bikes from other manufacturers. Most folks can go 4-5 miles on a bike if they can walk one mile, and that is a decent length test ride. If you know your commute is longer, further might be better. If anything hurts on the test ride, talk to the shop staff about it. A well fitting bike doesn't hurt, and *no* bike should hurt on a 5 mile ride. Depending on what hurts and why, the right solution may involve swapping parts. Saddles are a very common swap, but stems, handlebars and pedals are not a whole lot less common. If you need to swap a lot of parts, it can really add to the cost of the bike, so it pays to do a lot of test rides to find the bike that needs the smallest amount of work.

Faster than your husband is mostly a matter of you, not the bike. Hill climbing is a skill, and when I'm healthy, I have to wait at the tops of hills for my partner. My bike has 7 gears, his has 24... but I *like* hills, ride them often and squeeze every bit out of my gears. He hates hills, and really resists gearing down. The point where my bike is an advantage is I get full use of those 7 gears, because they match up well with what I can do (spin mostly). More gears wouldn't do a whole lot to make me faster, because I'm not strong enough gain anything from higher gearing.

Most bikes can handle a bit of touring, and a bike that does daily duty as a cargo hauler will be fine as long as it fits well. The main thing to look for in a cargo hauler is the chainstay length... 44-47cm is good, less you might find the bike handles oddly with a lot of weight on the rear wheel. It's pretty rare to find stock bikes with more than 45cm chainstays tho. Front baskets can work quite well, but they are a little fussier on how the front end is built than a rear rack is about chainstays... if the bike feels twitchy without a basket, odds are it'll be worse with one. It's common to see bikes built to be twitchier, but if you don't ride much now, the twitchy will make the bike feel fast while not actually *being* fast. In some cases, it can be flat out dangerous because the bike is hard to control.

No bike is going to be 100% corrosion resistant. A steel frame can be treated to minimize rust (the same way a car is), but the parts hanging on the frame need to be checked regularly to make sure they're in good shape. Aluminum frames don't rust, but they can still have corrosion issues, and the parts will still need checking. Figure you want at least one tune-up a year, maybe two if it's a daily rider. With practice, you can do basic checking yourself, so things get fixed before they're a serious problem.

It's pretty easy to get a relatively upright position on a step through frame. The problem is, most bike manufacturers assume that a strong woman who rides hard will prefer a more rigid diamond frame... so getting high quality parts on a step through can be a problem. And a more upright position is something of a disadvantage on a bike. For me it's no big deal, the 6-8 stop signs every mile will slow me down no matter what. For a stronger rider who has open roads to deal with, the extra wind resistance can be a problem. I'd really recommend trying some bikes that are very different from the ones you've posted because you'll learn a lot... a granny bike is quite effective for in town riding, and a touring bike with drop bars is great for long distances.