Yes, yes you can use any pedal on a ‘fixie’ but it will just be harder to skid unless you are totally confident you wont ‘pull out’ or become uncliped.
if you have not brought any pedals yet most people on this forum speak highly of ‘time atac’s’
You can use a normal spanner, shifter, or an allen key if the pedal permits. Somehow I think this is not what you want to know. Don’t forget about the reverse threading on the non-drive side.
I used to love Spd’s too coming from a ‘BMX racing’ background. When I started coming unclipped from my spd’s on the ‘fixie’ I switched to time’s after having them recommended to me by a few of the couriers round here. Such a nicer pedal, can’t believe Shimano haven’t done something to improve their design.