Hi DeAnna

Welcome to CLF!
I'll try to answer some of your questions....
Horseshoe Bay Beach is quite a walk from the main road if you use public transportation to get to it. It's all down hill, but sometimes people with bad knees and walking long distance problems have issues walking downhill so if your Grandmother is joining you, I would opt for the ship's tour to Horseshoe Bay, even though it is more expensive, as it will take you all the way down to the beach area and come pick you up with less walking for her.
The wine package was the same price onboard the ship that it was purchasing prior on our Brilliance cruise when my friends purchased it. Also, if you wait until you board you can see the bottles in each package. They usually set up a table with the available packages right outside of the Windjammer on embarkation day.
Your cabin is a corner aft balcony and a very desirable location for many cruisers! I've never stayed in a cabin in that location, but you will have a view from the back and possibly the side of the ship when on your balcony. Your balcony will also be longer in size than the standard balcony length so you may have a lounge chair or two out there. As to whether it will be chilly outside, it could be since you'll be in the Atlantic Ocean, but if you bring a sweater that would probably be all you would need. With the aft location some people say they feel a slight vibration from the engines but not really much ship "movement". All this is dependent on weather conditions and if you have calm seas.
If this is the 5 night cruise to Bermuda, there will only be one formal night during the cruise. You'll see women dressed in gowns or what I refer to as "what you would wear to someone's wedding". Whatever type of dress you're comfortable with between those and you should be fine
I'm sorry but I've never been to the perfume factory so I can't comment on it.
As to something to do with Grandmom, what does she like to do? Is she into history? Beaches? Shopping? Water activities like snorkeling? Bingo? Casinos?
The one thing I would recommend is going to the Ice Skating Show. Tickets for this go very fast so check the Cruise Compass (the daily paper) for the date and time they'll have the tickets available and make sure one in your party is there to get them for the 3 of you.
Irons are a fire hazard onboard ships. If you need ironing done you can send it to their laundry service for pressing only. Or you can hang what you need ironed in the bathroom while someone gets a shower or turn on the shower to try to steam it. If you "roll" your items when packing and unpack right away once onboard the ship you may not have to worry about it.