Looking for answers and possible questions to get covered before heading to vet

I have a cat that is around 2 years old that has always been a "lazy" cat, very laid back and chill and always an indoor cat. About 2.5 weeks ago she wondered on to our back porch and managed to get lost in out shop/under our house for several days. Has been fine up until Friday night/Saturday morning. Showed normal behavior (for the most part) up until that time as she has become very lethargic and unable to hold down anything more than water and KMR. I plan on getting her to the vet as soon as possible (since it has been the weekend and we don't have an emergency vet where I live.) Any possible assistance in figuring out what is wrong or any suggestions on what to ask the vet. 

Perhaps she ingested something that is poisonous.

Has she been seen yet?  Just tell the Vet exactly what you know.  They should ask YOU questions about what happened and how she is acting, etc. 

Hopefully they can figure out what is wrong and get her back to normal.  It's always such a worry when our little ones are sick

Took her to the vet Monday morning and told them what was going on. Said she had an ulcer on her younger (a flat white are all), a high fever (105*), and congestion in her lungs. She received an antibiotic shot, a steroid shot, and take home antibiotics that I must force feed her.

She is already showing some improvements like vocalizing, more active, and play fighting Luci (my 8month old cat). Refusing KMR and choosing only water so far today but her behavior is getting back to normal and fever seems to be gone or at least extremely low grade. Praying things stay on track and I can get some more nutritious things down her. Any suggestions.

Force feeding is the way to go if she is not eating on her own. Did they give you any A/D or other type of food that works well in a syringe?  Did they explain to you how to do it?  If not, you need to water down a pate canned food until it is a creamy consistency, creamy enough to easily go in and out of a syringe. Hopefully they gave you some good size syringes?

Here is a video that shows how to syringe feed.  http://www.thecatsite.com/t/227858/syringe-feeding-lucky-video-if-your-cat-is-not-eating

She is able to hold down solids... Thank the lord. Wanted nothing to do with liquid type foods. So happy she is feeling better. Also while it was a quick visit to the vet... I am pleased that he takes the time to call and check on his patients the next day.

Yes, I always appreciate a follow-up call from our Vet asking about the furkids.

As far as getting more nutrition into her, perhaps feed her some kitten canned food.  It's more nutritious, and more caloric.  You can also see if she'll eat some scrambled eggs, even cooked in butter (unsalted would be best), or mix raw egg yolk into her canned food.  Some cats love egg yolks, some don't., but they are very  nutritious.  Just don't feed her the whites if you are giving them raw.  Pate style wet food is usually more caloric.