I'm switching career from Corporate (Finance/ Accounting) to Higher education.
Good idea! hahahah, that is what I would do...
What should be the length of the SOP?
Depends on the school... but... if they give no guidance, how about 2-3 pages?
Should I emphasis on my 10 years work experience and its transferable skills/ knowledge?
Good idea. Real world experience is key.
If you are clever, you can incorporate lots of good things, making the essay like a candy bar jam-packed with nuts.
BUT for your central theme, it is good to use something sort of inspirational. Let the reader in on your revelation -- that you will infuse your life's work with meaning if you can affect the learning processes of countless scholars. that is what I would to.
My friend from high school switched majors from Management info systems to education, and he was SO happy. Instead of making the conservative choice, he decided to approach life in a "heartful" way.