rust in one of these old tanks is not uncommon, there are a number of ways to remedy that with out replacing the tank. it's such a common topic that you should do a search on this or another forum for details rather than me repeat it.
you will probably have to find exhaust specifically for a cb/cl/sl 200. either that or find after market pipes with the same diameter header.
most cb hand controls are going to be universal. though as i experienced just today the wiring colors may not match the scheme for your model making for some work deciphering whats what.
that said, many of the cb/cl/sl parts from most years are universal. but when you start talking about engine or carbs specifics you want to check for compatibility before you invest.
some are, some aren't. The best way to check is to get on a place like honda parts direct and check what bikes share part numbers.
I can tell you right off the bat the cb200's gas tank is completely unique, and I am willing to bet good money the muffler is too. The control assemblies tend to be universal to the honda line with small changes (eg sometimes the right hand bar switch has a starter button sometimes it doesn't). I am not going to go out on a limb and say any lever will work because I don't remember if the cb200 is disc or drum front.