OnTheGo

You asked what to do with the sleeves of the shirts after you made the skirts (which are so cute). Here are a few suggestions:
Cut the top part of a long sleeve in a half moon to form a crotch and all you have to sew is the one crotch seam to join the 2 sleeves/legs and make a casing across the top for elastic to make a childs pr. of pants for pj's or like sweat pants. See drawing.

Short sleeves: make darts in the top part, leaving the hemmed part for the bottom of a cap. Make 4 to 6 darts to take in the width of opening, then make a seam. I bought a fleece cap made this way. If the crown doesn't exactly look right, you could make a yo-yo to trim it. Picture included of the one I bought.

Cut crosswise and sew a tube & make about 3 channels to run elastic for a head band which can also be trimmed with a yo-yo.

If the sleeve is small, cut across into loops to use on a potholder weaving loom. They are very expensive to buy.

You can also cut several thicknesses and sew together for a hot pad or pot holder.