The JoJo manga is mainly presented in black and white. However, there might be some special editions or colored illustrations for promotional purposes, but the standard version is not in color.
Sure, JoJo Part 7 manga is available in English. But the availability might vary depending on where you look. Some physical bookstores or online platforms might have it in stock.
In my opinion, Part 3: Stardust Crusaders has an amazing story. It's about the Joestar group traveling to Egypt to defeat DIO. The journey is filled with various Stand battles, each one unique and exciting. There are new characters introduced along the way, and the development of their relationships and powers makes for a great story. It also has a lot of iconic moments that fans love.