Unlike AMCAS, there is less room for ECs. My employment history is much abbreviated, although I doubt that they want to know much about my house painting 10 years ago.
I don't recall the limit on words for the volunteer positions/internships response. I was fairy pithy about the descriptions, but the activities were fairly self-explanatory. Some explanation of your role & responsibilities may be beneficial if the activity or award is not straightforward.
Myriad opinons on optimal EC construction can be found on the pre-allo page as well.
I have already submitted, so I have to stop thinking about this, or I am going to have a fit of second-guessing. AARGH!