Answer: You should be fine with the apples. The Granny Smith and Fuji should bloom at the same time so they will provide pollen for each other. (Granny Smith is sometimes listed as self fruitful but seems to do better with a pollen source.) Many peaches are self fruitful but not all, so it depends which peaches you bought. The plums also may or may not, depending on the specific varieties you have.
You can plant all of these in a grove together, yes. Plant the fruiting pairs in close proximity for best results. It is also easier to care for the trees in terms of scouting and spraying if the same types are next to each other, meaning apples are next to apples and peaches are next to peaches. Be sure to allow space between them for each tree to reach its mature size and still allow for light and air in between.
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