I received this reply from Ed, today regarding keywords, It might be helpful to us all.
Thanks for all your support on NP, it's really appreciated.
I can't really think of a better answer to the keyword issue than a post that I made on a UK forum.
Setting multiple keywords - with commas, without commas or otherwise separated - often doesn't achieve much, as you won't get, say, 2 ads from keyword A, 2 from keyword B, 2 from keyword C etc. etc.
If you set 4 distinct keywords, say: Cars Trucks Motorbikes Insurance, then Google will try and firstly decipher this as one phrase "Cars Trucks Motorbikes Insurance" with little joy. They may then try and see if there are any phrases within the phrase. "Cars Trucks", "Trucks Motorbikes" "Motorbikes Insurance" (possible you'll get some results for this). Failing this, they will normally pick what they see as the 'strongest keyword and return ads for that - in this case, I would presume "cars" and ignore the other keywords, rendering them - and therefore the need to set them - redundant.
As a result, I always feel that setting multiple keywords is somewhat futile, though we see it happen a lot. If you do set them, I'd say use a comma though, as stated above, I don't really think it achieves much. It is a far better strategy to rotate individually through keywords you'd be interested in using and see which ones work out best on their own.
In the case of a phrase consisting of several words (i.e. "DVD players" "car insurance" "Far East Travel"), then no commas are necessary.
I hope this sorts it out a bit. It seems that Google doesn't really understand multiple keywords very well!
Let me know if you have any other queries,
Best regards,
Ed