For training an outdoor cat to use a box, you might put in dirt, with the litter.
You can gradually decrease the amount of dirt to litter, until it's pure litter.
If you have unaltered (not fixed) cats, do consider having them fixed. If you have a full male cat, you'll know why. He will stink up the house. As for the female, it's really best, for her health, and to help stop the overpopulation problem and have her fixed as well.
For scratching, try scratching posts of different materials. Sisal is very popular, also cardboard.
Good Luck
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