All depends on how much you sweat, how fast you go, whether you wuss out every time the roads are wet or god forbid, it rains. I favour full lycra and a high vis jacket of some sort most of the year or a bright S/S jersey in hotter summer weather.
As for lights, I use a smart on the front, flashing, and a cateye 5 LED on the rear, also flashing. Combined with my off road 3xcree Helmet light for front lighting on unlit unclassified and B roads (I commute in the country).
As for guards, I prefer to just stick waterproof 3/4 shorts on when it rains, but standard opinion is SKS for full guards. They do a clip-on which will fit a 35mm cross tyre which I might consider buying soon but not really sure I need them.