Replace all the fuses. Don't assume they are good.
Unless you know its been done, replace the vacuum hoses connected to the idle control valve. If one of those goes, you are stranded. It happened to me.
I'd look at all the hoses as suspect unless you have a receipt showing their recent replacement date.
As for the radiator neck, I do not know if the CE has the same radiator as the 300E -- if it does not have the reinforced neck, it will break on you. That can be checked quite easily though.
Look at the thermostat housing -- is it plastic or metal? If plastic, order the metal upgrade now and replace it. Don't wait for that one. Probably already done by a previous owner but check anyway.
When was the water pump replaced, if at all? Never? It will go when you least expect it.
Check the other vacuum hoses and lines for dry rot, etc. I'd spend the dollars to replace them anyway. Pretty cheap insurance.
Change the oil hot and often.
Drive it often:-) MBs hate sitting around.