Upgrading to v. 1.5.2 – questions

The suggested fix for my comment spam problem, noted here (Running version 1.2 – host supplied; dying from comment spam) was to upgrade to 1.5.2 and then make use of certain plugins.

My principal concern has to do with the changes I had to laboriously make in some php files in order to set things up. I want to make sure that I don’t have to go through that process again if I install a new version. Assuming I find and acquire this version, what are some of the things I need to watch out for? Also, does the hosting service have to be involved in the process in some way?

Thanks.