It really depends on what you want from your league and what type of rules you use.
If you have daily moves, then it might be a good idea to set a max of 162 for each position. Otherwise, those that have more time on their hands to make those daily moves might be able to exploit days off to get more then 162 games of stats at each position. If you use weekly moves, this is much less of a problem.
I generally am against setting minimums, but I understand why some leagues like to do it. The most typical minimums I've seen are 1100 IP for the year, counting all your pitchers. This pretty much means you have draft starting pitching, otherwise you will never make the minimum.
However, it is fun for leagues to have no minimums, too. It gives a owner more options on draft day as to how he wants to draft his team. He can decide to punt wins, if he wants and draft all relievers, if there are no minimums.
If you are worried about it, the easiest thing to do is to set your league to weekly transactions and a 1100 IP minimum. This covers most of the potential "exploits", if you want to use that term.