#1 is completely wrong. Use of document fragments is much faster than innerHTML. This way your dom operations occur in memory and the results are pushed to the dom in one operation. Most of the rest of the tips are valid.
No Geuis. Setting innerHTML works faster than DOM methods. Please test.
it isnt completely wrong, just slightly confusing. I am guessing he means using innerHTML over working on live dom nodes which are very expensive. documentfragments should definitely be worth mentioning though.