Eating frozen pizza might just hurt your teeth a little if you try to eat it, you know, since it's frozen solid..!
Seriously though, you should be fine haha. As long as you're not eating it every day and still have a balanced and varied diet, go for it. Everything in moderation.
Sure, but you're going to find these things in much, much smaller amounts in frozen food than you are take-away pizza for example, that's why the latter tastes so damn good Either way, as I said above, if it's a once in a while treat it's unlikely to cause any significant level of harm.