Changing from HTML to WordPress... Does it affect ranking?

[sniperhiga]

Website doing well in SERPS and got good pagerank. I want to change regular HTML pages with WordPress and redesign it. So it will switch from /index.html to /index.php. (Hosting / ip / domain the same!)

1. Will it affect search engine rankings?

2. Will it affect pagerank?

3. Should i redirect pages with content which will go into newest WordPress blog?

4. It will slow down traffic a little, but after Google, Yahoo, MSN reindex it it will come back... Is it correct?

5. Will it destroy my year of link building.

[Taltos]

Bummer, no one answered this. I am very curious. I would think that as long and the content doesn't change drastically so the the keywords are all still relative, you would be OK after some fluctuation. Have you optimized multiple pages for different keywords and would the page still exist in the new WordPress version? Most of the links are just to the domain with no page so index.html or index.php won't make that much difference? Or are the links to a very specific page?