As rayaans points out, washing up liquid will remove everything. The water that remains is going to be sitting directly on the paint with no wax, so it's going to dry there and leave water marks. Using proper car shampoo will save you time and work a lot better.
If your garden vac has a blow mode, and blows clean air (no grit!) then that'll cut down the amount of work you need to do. A drying towel is what you want to get the rest off. Start at the top and work downwards - the dirtiest grittiest bits are at the bottom.
As far as soft / hard goes, yesterday I used a DA with Meguiars 105 and an orange hex logic pad to take out some small scratches, swirls and marks, and I'd not say the paint is soft. It took a normal amount of time and effort to get the job done. German finishes are usually hard, but having dealt with several panels, I'd class ours as medium.