Practice helps, but initial athleticism matters a lot. There were years when I practiced 20 hours/week, under first class coaches, but I still have trouble with the most basic turns, spins and jumps. Accept that she will be better, and be happy for her.
Some rinks supply rental skates that provide good ankle support, some don't, and also vary in what widths they carry. Check out several pair at the rink, to see if something fits and meets your needs. You may be able to use rentals, especially if you arrive early enough to always ask for the same (numbered?) pair. I like to have my boots on before the session starts - the ice is least crowded during the first 10-20 minutes.
As a big guy, if you buy, the major specialty stores (Anaheim?) are unlikely to have your size in stock, so you can't try the skates on, which is otherwise a great idea. So you need a good fitter to help you order. Since a lot of people mention the store in Anaheim, it may be worthwhile.
Make sure the fitter knows how to adjust the skates you buy for balance! Some fitters can't handle non-leather soles, or blades held on by rivets, and a few don't know how to adjust balance at all.
I believe one of the best things we can do is to learn how to fall without hurting ourselves. Practice, to speed up your reflexes. Start low, from sitting position, and work your way up. See my page
http://mgrunes.com/falling.html You have more padding then some, but you also can put more force on your body.
Hockey boots are harder to balance at first, and they work a little differently. If you decide to get lessons with the lady friend, ask her whether she would enjoy hockey or figure skating more - and get boots that fit that purpose. Also check what types of skating are available during your convenient hours - e.g., if there are no "stick and puck" practices and pick up hockey games sessions for adults, hockey is a lost cause.
You lift 300 pounds every time you move, so you
are strong! I don't think it is realistic to expect to lose weight very quickly. Books say that if you lose over about .1 pounds/day on a prolonged basis, you probably weaken your heart, unless you do serious physical training. Buy for your current size, then add a little filler inside your boots when you lose weight. If you buy small, it's a lot of pain and hassle.
My page on modifying boots:
http://mgrunes.com/boots/boots.htmlThough I've changed my mind on boot fit from when I wrote that, after talking to experts: getting the position of the ball of your foot right, so the back of your heel touches while the ball of your foot can bend at the place the insole bends, is much more important than getting the length right - as long as the boot doesn't press at the front of or around the sides of your toes. Also, different brands of boot are designed to fit your foot differently, so the way the foot is measured (e.g., standing or sitting, and what the size numbers mean) depend entirely on the brand of boot. You need a knowledgeable fitter.
BTW, if you have problems with poor blood circulation (e.g., if your feet tingle or go numb in snug boots, or you can't feel how your feet fit the boots all over), stop, and ask your doctor if you can safely wear snug fitting boots. If not, take her swimming instead.