Welcome aboard the one below!
You started off right by asking before crash diving in. I haven't tried SH5 because of the bad reviews about it. I have SH4 and think it's great, even before mods. My suggestion is go to Amazon.com (there is a link to it from this site) and buy SH4 Gold. You will get the latest version. Most of the mods are written for this version.
Since you're still run aground, go clean my office.