Q: Do Meta Keywords Still Matter? Should I remove all the meta keyword data from the site? 
A: Most SEO’s would agree that meta keywords are no longer used as a ranking factor in Google and Yahoo and Bing.
While it isn’t a “Top Secret” what you are trying to accomplish with a page , But deleting this tag can prevent your competition from sniffing out your keywords (They still can find it, but they have to put more effort into it) and you  may carelessly giving them your formula, especially true  for long-tail keywords.
So …

Q:Should I add nofollow to banner and text ads?
A:In general all the advertising networks or ad management systems (plug-ins) already do add block outs using robot.txt and bunch of other methods,
But you are selling your ads directly then, Yes whether it is a text or an image ad you should put nofollow tag in them.

Q: Why Google PageRank is not updating often?
A: Google updates their page rank database every 3 to 4 months and it takes time,  So do not get obsessed by it all the time and refreshing your page 5 times a day which won’t speed it out.
Instead, Think about other features of your site:

ROI (Return on Investment)
Link Building
Website design and overall website performance
Website speed

And i know it is nice to have higher page rank and for corporate users it is still an achievement metrics for website KPI and it’s nice tell …