1. Why did the brothers return Joseph’s coat intact if they claimed he was mauled by a beast? 2. Why does it say and they sent it (the coat) and later, that they brought it? Which did they do?

Actually, the Soforno answers both your questions at once. The word "vay'shalchu" in 37;32 he translates as "they cut up" in order to make it appear that Yosef was mauled by a beast. (See RaDaK and Seforno for derivation of that translation) Another approach, 1. The colored coat was an outer garment (see Rashi verse 23), that Yosef would not wear while sleeping. The animal would have pounced on Yosef while asleep and dragged him away, leaving the garment behind. 2. The brothers sent the cloak in the hands of Yehudah, as their representative (Midrash) so it was if all of them brought it through his agency. (THe Ramban has another few variations on this theme)