Ahhh...my forte! I took almost weekly day trips to DL alone with DD from 4mo-20mo. We also travelled to WDW alone at 15mo and several times since then.
Stroller - Definitely take your own! While I really like the rental strollers and think they are very convenient for an older child, I on't think that your DD will be very comfortable in the rentals that young. If you have one, I would recommend anything that folds umbrella style. At 15mo we had a Pliko P3. On subsequent trips it was a Maclaren Triumph. I

travelling with the Maclaren. Use the stroller in the airport to help you get to the gate and then gate check it.
We had a Hip Hammock carrier for DD as well and that was invaluable when at WDW alone. Also, I found it easiest to carry everything in a backpack. When it came time to load the buses, I would put DD in the carrier (very easy at 15mo, but I still did it this was up until she was 3yo) while waiting in line for the bus. As the bus approached, I would put on my backpack and then fold the stroller. For boarding, DD would be in the carrier on one hip and I'd use the other hand to carry the stroller on and hold it during the trip. I would add that probably 1 out of 3 or 4 trips, someone - usually a dad - one offer to help me get the stroller on and then insist on holding it throughout the trip.
Buffets - our number one table service of choice. Gotta hit all of those character meals! At 15mo, my DD was not walking so having her walk next to me wasn't even an option. For buffets, I would just carry her and fill one plate at a time. Sometimes it was easier to stack two plates and then put things for both of us on the top plate. There is enough ledge at the buffet to support the plate while you serve. When we got to the table, I would just move her portion to the second plate. Other times, we would just take two trips to the buffet for the first go around. It added a few minutes to our meal times, but then they were easily made up for in only having to wait for the two of us (as opposed to 4 or 5 people in the group) eating, riding rides, walking, etc.
Line waiting - if you have a carrier or sling that DD can still use, I would recommend bringing it. It's a lot harded to hold the little one in line when there isn't anyone to pass her off too. Again, my DD wasn't walking yet so I did more carrying than you might, though she would stand in line holding onto the rails when we weren't moving.
Room location - if you have the option (I'm not familiar with DVC processes), consider asking for a room closer to the bus stops, etc. When I mention that I am travelling alone with DD, the resorts are often willing to help me with a room closer to the main areas or in a busy area (DH feels better if he knows we are in a more highly trafficed area when we travel alone).
Counter service - Counter service restaurants were almost harder at first than buffets. Once I figured them out, they got much easier. I always use my stroller to get through the lines. The registers at at least one, if not both, far ends are open on one side so that they can accommodate wheelchairs. I use these registers and keep the stroller with me. Often there is a little bit of wall area where I can push it just out of the way of those getting their food, but still be in easy reach myself. After getting the food, I carry it with one hand and push the stroller with the other. Don't forget to stop for straws, condiments, etc before you get back to the table and get too situated.
Pictures - Photopass is a godsent for solo parents! I finally get to be in a whole lot more of the pictures from our trips. Also, don't hesistate to ask CMs or even other guests to take a picture for you. PhotoPass CMs will even take one with your camera after they take theirs.
Nighttime stuff - Not particularly unique to travelling alone, but my DD was a sleep-anywhere kind of kid (and still is!). I would take her pajamas to the parks with us each day. Around 8 or so, we would stop in the bathroom and get her ready for bed. Then, she would nod off whenever she was ready and I could spend the evening strolling around the parks and/or enjoying the nighttime shows. When I was ready to head back, she was all ready to just put into bed.
Have a great time. I love travelling and Disney, as does DD at only 4yo. DH, on the other hand, could think of few things worse. We have taken 4 trips to WDW on our own, plus 2 with my little sister (8yo or so at the time). I think you'll have a marvelous time!! If you think of any other questions, just ask away.