When I make a new adgroup with it's own set of keywords, should I be linking to a different page than other ad groups? I assume that way I can optimize the page for that set of keywords in the new group... If so, then doesn't that mean I basically need a new landing page for each ad group?
The benefit to separate landing pages is that you can make each landing page very relevant to the ad that targets it. Therefore if you have several ad groups that are all relevant to the same landing page then you do not need a unique landing page for each ad group. Of course you will want to test the effectiveness of different landing pages to see how this works for your specific campaign. Good Luck.
no you don't have to, but i would recommend separate landing pages when the keywords are very different from each other.
You're not supposed to but it will greatly help your conversions if you make separate landing pages that are specifically relevant to your adgroup.
An example If i'm looking to buy a Used BMW Z4 and therefore search for a Used BMW Z4 what would be the best landing page for me, a generic home page with (another) search facility or a page telling about the latest deals on the BMW Z4? Separate landing pages are better for the end user and Google reward this with a higher quality score so better for you