1. The longer you can leave penetrating fluid on for, the better. 24 or even 48 hours is going to help way more than just 30 mins.
2. Ramps to get it up, then jack stands as well just in case.
3. Proper tool is peanuts, but I usually just disconnect then put a spanner on them and remove whilst the cats are still on the car. Or whatever works, really.
4. I always prefer manual tools to impact stuff as I can feel exactly what is going on, but each to their own.