Indexing speed and ranking

Hello,

Recently the number of unique visitors bring by Google organic search dropped. Out of the blue. The number of indexed pages started to grow.

I compared the Google cache for several of my pages with one of my competitors (a bigger one). The cache for my pages is 4-5 days old, while the cache for my competitors pages are updated daily. First I tried to explain the age of 4-5 days for the cache using the nature of the pages. They are product pages which don't change too often. But I checked for several days my competitor's pages and they don't change either.

Does anybody know why the cache for my pages is renewed only once on several days and not daily? Is this affecting my rankings?

No, this will not affect your rankings if your content is not getting update. But if your are updating it frequently, fast crawling is required so that SE can rank you for the new content.

What I'm facing these days when I changed the server of my article directory it has now just 10 unique visitors per day but it had around 300 unique visitors per day........ I just updated server yesterday and today it is just 10 visitors today, I am not sure that in few days it would recover or not.

The main thing it has around 150000 pages indexed, this is the main thing.