Decided to take in a stray - need all the advice I can get

Hello everyone,

I finally convinced my fiance to take in a stray that has been coming around since last July. Her name is Oskar (we thought it's a male), she's about a year old and has been living in our backyard and shed. Last year we took in her kitten, Catsby, when he was about 4 weeks old. We also have a 1 year old (Uszka). After we took in Catsby, we trapped Oskar and got her spayed. Although the neighborhood is generally safe and she really only stays in our backyard, I want her to be safe and healthy for many more years to come. She doesn't let me touch her but she snuggles up to me when she gets food in the AM and PM, and she further LOOOOVES playing with me on the porch. There's also no bad blood whatsoever between her and Catsby & Uszka. They sniff each other through the screen door and Usz often tries to play, though Oskar doesn't really understand that yet. She often hangs out on the porch for over an hour in the AM and PM, and often just stared inside. Of course unless I come out to play. 

Our plan is to trap her, get her to our vet right away, run tests for everything that could pose a danger to our babies, and then have her in a room for a few days to acclimate while allowing her to explore with the others being locked away. She has come inside already when Catsby & Uszka are locked in a room (I know I know, this is dangerous given I don't know what she might have), and she's super curious about everything in the house (TV, toys, etc). 

My specific concerns questions are:

1) Litter box training: I figured I will put 2 litter boxes with dirt and some litter in the room we will keep her in for the first few days to get her adjusted to using a box. I do wonder about how quickly I can make the transition from dirt to litter? Or do you have other ideas/suggestions?

2) I am no stranger to slow intros (It took us 3 weeks to introduce Catsby & Uszka and now they are BFFs), but I wonder how soon I should allow them to interact. They know each other pretty well but I wonder if things will change when she's actually in the house.

3) We have a weekend come up at the end of May where we have to go out of town and I am debating whether to wait until after that, given that I am not sure if Oskar will be ok being left with the others for a full weekend with a pet sitter stopping by 2x/day.

 4) I am also so torn between taking her in and letting her live outside. All I want is for her to be happy and healthy. I worry that she will be so so scared when we take her in (trapping, vet, new environment, no escape outside). But then again, people do drive like jerks in our neighborhood and we live in a wooded area with lots of other wild animals.

I'd love some any feedback and any advice I can get. This seems so overwhelming and I want to do things right.

Thanks a lot!!!

Cats naturally dig a hole and bury their business, so litter box training is really easy once they know where it is. I'd get some litter that doesn't have a scent to it just to start her off and eventually transition to whatever litter you typically use.

Once she is cleared medically and has had time to adapt to being in a house it'll probably go smoothly. If there is any fighting or stress then go back to the beginning. 

In my opinion, anything is better than being left outside, even if it's a weekend of being alone in a separate bedroom / bathroom. I would take her in before your trip if at all possible.

I think you're a great person for taking in Oskar, she will have a better life in a home where the things in the outside world cannot get to her ^_^

Thanks for your input TNRcatWoman! We will try to trap her tomorrow morning and get the whole process started.

I do wonder about another thing: I want to give Oskar a few days to explore the house without the other cats being around BUT, how would I get her back into the room she will be staying in for the first few days? It's not like I can pick her up and put her into the room. 

I've noticed with all my cats that when they get scared they all retreat to the room where they were introduced to the house, so I don't think you'll have much of an issue getting Oskar back into the room. Also food will help with that! 

Hope you managed to trap/vet check her okay. 

If I had been a boy my parents were going to name me Oskar!