The suggestion to run a 6mm screw in partially ( as a "starter" for the 7mm), and especially the suggestion to use a bar of soap (as a lubricant) on the 7 mm screws
should get your 7mm footstrap screws in your new boards with as few issues as
As far as screwdrivers, make sure you have a good high quality #3 Phillips Screwdriver.
High quality #3 Phillips screwdrivers normally have a hardened and surface treated tip
(normally it's black oxided coated and while the shank may be chromed, the tip is black).
The hardened tip will have good "geometry" and surface finish characteristics that help the tip lock into the softer SS screw and will not damage or strip the cross recess (Phillips) drive in the head of the screw.
DO NOT use a power drill/driver as this will run the screws in too fast and heat up the
plastic of the insert (due to friction from the very tight screw).
I too, like Ola, really did not have any significant issues with the 6mmx 28 screws, but I always used soap as a lubricant, used the correct screwdriver with the right tip material and geometry, ran a bare screw into the holes to give the screw a smooth start, and clamped the K9 locks and oval plates with a "C" clamp to compress them and get the K9 lock spikes to pierce/penetrate the nylon in the footstrap.
If you take your time; use the correct tools and lubricant; you should be able to install your footstraps and expect them to last the life of the board.
Hope this helps,