Just leave it for now. Whether I've used kits or AG I leave for 2 weeks before I do anything (unless a major obvious issue like the Krausen coming out of FV!) It does most of its stuff first few days, so you could take a sample in a few days and if it looks stuck, get a well sanitised spoon/paddle and give it a very gentle stir, no splashing if you can, and leave for a few days. Don't get hung up on visual activity, yeast does stuff on the sly! What temp is it at?
If after a few more days still stuck, I've used amalyse before to get it going a bit more, and you could always order another packet of yeast now to arrive in a few days if needed.
White sediment, not sure to be honest, sorry.