Sleepovers are so fun!
Just ask the child to bring what they want to sleep in....a favorite blanket or pillow, their toothbrush, a change of clothes.
(Some kids are fine with using whatever blankets or pillows you have on hand).
As for dinner, make it simple and kid friendly. Make homemade hamburgers or spaghetti. Or, pick up a take and bake pizza. Let them put on a movie and have some popcorn.
For breakfast, they can have cereal, but it's fun to make pancakes or french toast in the morning for them, at least for me.
What time they arrive depends on everyone's schedule. Afternoon is a good time but not always possible. (I preferred Fridays after school so my kids could be rested and back in the swing for the rest of the weekend). When they leave shouldn't have to be too early unless someone has a committment the next day.
Just agree with the mom when the child will be brought over and picked up, or you'll pick him up and bring him home.
Make sure you have snacks like fruit or veggies and pretzels. All the kids that came to my house were introduced to "bubble water". I hate to say it, but I had a few kids who were die hard soda fans because they were allowed to have it at home. Surprisingly, all the kids loved the bubble water alternative. (It's seltzer water, 78 cents for a two-litre at Winco). I gave them the choice of having it plain or with a little lemon or orange squeezed in for flavor.
Kids are pretty good at enteraining themselves. It's fun being at someone else's house to sleep.
The more you have sleepovers, the more you'll get a routine and find what works. We had kids that were over so much that they had their own toothbrush and things at my house. Same thing with places my kids went often.
Don't worry too much about it. It doesn't have to be a big production. You might really have fun yourself. I know I always did.
Regarding showering, I have a couple of friends who LOVED their sons staying with me because I would simply say that everyone had to take a turn in the shower before bed. At home, it was an argument, but at my house, they just got right in. No magic involved, kids often easily do things for other people they don't easily do at home. My own nephew was the same way.
Little boys can get stinky and frankly, the warm shower in the evening helped them settle down and was the clear signal it was time for pajamas and winding down. I had a rule they were not allowed to lock the bathroom door in case they needed something or slipped. The boys that stayed over were actually easier than some of the girls I had with my daughter.
Like I said, you'll figure out a routine. Don't be afraid to get feedback from the other mom.