please don't mind me for asking this newbie question about Google ranking. I know that in order to get ranked the page has to be crawled by Google bots, I have had a page example of which I will get a better understanding of how the system works with Google.

I have made a page on my website last month, it got indexed pretty quickly, then I found that it's in Google's page 15 on my keyword as a start, next day it made it to page 13, then after a week it was jumping back and forth in page 17/18 up to 20.

Now a month passed by, when and it isn't listed in any position of that 'keyword' sometimes I will find it in page 30, but later I won't find it anywhere, keep happening this way these days.

Even if it isn't listed in any page for my keyword if I do a search for "site:thepageadress" it will be listed which means I'm not penalized and my page is there for google to see, but it isn't in the search result for my keyword. But when I write "site:thepage_adress" and I hit "search tools" option and click on "Past day" or "past week" it isn't listed, it is only listed when I click on "Past month" which I think means that Google indexed the page, looked at it once when I published it, and never looked at it again, is this a fair statement?

So two questions that comes to mind here.

1- Should Google keep looking at a page even if I haven't changed any info for it? and is this an indication for me that my page is doing fine? or is it normal that Google see's it once and thats it?

2- Why and how to fix the fact that my page keeps jumping back and forth in the ranking result for keyword, and sometimes it isn't even listed, what does that mean?

Sorry for the long msg, I hope to god that somebody help me with this. Thank you!