road pedals like shimano SPD-R or look KEO are better for long distances, but if you don't want to use clipless, that's fine too.

the cheapest form of foot retention will be these: http://powergrips.mrpbike.com/

but be aware that cycling shoes have a rigid sole to better support your foot, which gives more efficiency while pedalling.

just do a search on clipless pedals in this forum for the benefits of using them.