First off, I'm not being rude, but everyone refers to Hard Light in the short form as HLP. Just to eliminate any confusion.
Second, if you want an all-in-one solution, you can download the SCP pack made by Shivan_SPS. It's in the highlights, or search for his thread in General Freespace. His pack, though I haven't tested it, should be a one-stop easy install of FS2 + recent version of the SCP and MediaVP. If you go the other route, picking and choosing must haves, get a good SCP build, along with the MediaVP. It's important to have the MediaVP to have all of the nice graphical enhancements. Having the latest build along with the latest MediaVP version should give you all that you need in order to experience FS2 at it's best to this day. It only gets better though, so do keep up to date with the new builds. Also, since it's commonly used, Shivan_SPS has created a VP (a VP is a data file for FS2, everyone usually refers to them as VP's) containing the nebula backgrounds made by Lightspeed. I'd grab that VP as well, as a lot of campaigns will utilize these backgrounds.
As far as campaigns go, I'm going to suggest Derelict, which was made by an old team of modders, renewed by Blaise Russel, and has been completely voice-acted and brought up to spec with the SCP. Other campaigns I suggest are the campaigns made by Ransom Arceihn, the campaigns by Blaise Russel, and checking out the brand spankin new version of the FSPort, to play FS1 using the FSO builds. If you're in the mood for funny, Goober5000's campaign called Deus Ex Machina is absolutely hilarious. Then Axem's Just Another Day series is another great funny campaign set to try.
