I bought cheap Ryobi tools at Home Depot - 18V lithium powered. Drill, impact driver, circular saw, sawzall & flashlight. My impression going into this deal was that I was buying one step up from junk and that I was prepared to be disappointed.
Man, was I wrong!
The Ryobi tools have proven to be excellent - punching well above their weight. My biggest surprise came with the circular saw. I thought it was a toy. Now I find it's my "go to" saw, with my expensive corded saws gathering dust under the work bench.
For what you're doing I would highly recommend a cordless circular saw for the job. If using treated wood, don't forget to apply the end cut treatment to ensure rot doesn't set in.
As for screws, deck screws will do the job quite nicely - coated 3" screws driven with an impact driver. NOTE - most "head stripping" occurs because the person on the driver is not aligned well with the screw. HINT - buy a 6" or 8" driver bit to make the engagement angle between screw and driver more obvious to the eye.
Also, as a Canadian I have to say that it frustrates me no end to hear screws described as "square head"... That square head design is actually a patented design with the patent owned by P.L. Robertson & Co. I think the patent has now expired, hence the proliferation of "square head" screws. The Robertson (or square) drive is far superior to Phillips for high-torque situations like driving through wood.
Fun sidebar story... In my father's furniture business we used to buy Robertson screws from P.L. Robertson by the 50lb box. I would usually pick up 200-400lbs of them and that would do us for a little less than two months. I still have a pair of P.L. Robertson red-handled screwdrivers (Robertson #8, now what in the US is called square #2) and an 8" power driver bit. That power driver bit has certainly driven over 100,000 screws
in my hands and is still the best bit I own. P.L. Robertson screws and tools were the very best that money could buy.
