H1 tag title

I am adding about 20 pages to my site on a very closely related topic and started wording the h1 tag at the beginning of each the same except for the 1st word for example, walking by the light of day and the next could be eating by the light of day, and swimming by the light of day. I thought it would make things simple because things were so related it might be better for them to be almost the same. But then I started thinking should I mix the wording up more so google doesn't think it is going to be duplicate content.

One thing off this topic was something I started doing that I wanted to know if i shouldn't be doing is, I started resubmitting my site map to google after I added a new web page thinking it would get my new page indexed sooner. The only problem is the 2 times I did this my site went from page 12 in the search results to about page 70. The first time this happened I didn't think about it but the second time I started thinking did I do this because a resubmitted my site map. Has anyone heard of anything like this happening and should I stop this.

I can't thinking of anything else that could be causing my site to move so far back because before I started resubmitting my site map after putting up a new page this never happened. I would add a new page and the site would just stay where it was. thanks Mark