MSDE does not install any of the tools by default so you must have installed them from another source. So, you likely have 2 different issues.
Take a look at the SQL Error Logs to determine why MSDE won't start.
I doubt resolving the MSDE start issue will fix the SQL EM issue since it appears MMC can't initalize the SQLEM snap in. So you may wind up reinstalling SQL Clients to get that back, probably the fastest way to resolution for that issue.