The laptop uses Phillips #00 screws like every other PC laptop I’ve worked on - but there are multiple lengths that were used. If this is your first run working on the laptop, you really need to sort the screws. I didn’t bother in the guide because I know where they go and have dealt with enough HP machines to know.
In order to get to the hard drive, the ENTIRE laptop needs to be taken apart. I have a guide up for this, but there are multiple reports of a specific variation in the battery bay I never had to deal with where there are two extra screws that need to be removed if yours isn't an “exact match”. No other differences have been reported so far.
Once you remove the palmrest, the hard drive is able to come out without additional screws. The issue on this laptop is how annoying it is to replace. The guide can be found here.