Hi,
1. The debugging instructions there have always helped us find the issue when we had to look into it. Did you get anything with the payment log of HikaShop with the debug setting of the payment plugin activated ? If yes, then the answer should be in the debug data logged in there, if not, then you have to look at the apache access log for the IPN notification URL. If you find it there, it should give information about a redirect, or an access denied (meaning that the website refused PayPal the access to the notification URL for one reason or another, and the data in the access log should help identifying the cause). If you don't, then it means that PayPal is not even sending the payment notification, which is probably because you turned on the "enable validation mode" setting of the PayPal payment method, which is one of the points to check that are mentioned before looking at the logs.
2. Sure. Go in the orders listing and use the dropdown there to change the status for the order.