Macross is confusing? Just be thankful you're not looking into Gundam
The titles are (in the real-world order they were released):
1982: (The Super Dimensional Fortress) Macross [R1 DVD by ADV]
1984: (The Super Dimensional Fortress) Macross: Do You Remember Love [Ancient UK VHS]
1987: (The Super Dimensional Fortress) Macross: Flashback 2012 [Japanese R2 DVD]
1992: (The Super Dimensional Fortress) Macross II: Lovers' Again [R1 DVD - Manga]
1994: Macross Plus [UK R2 DVD - Manga]
1994/5/5/7: Macross 7 / The Galaxy is Calling Me! / Encore / Dynamite [All Japanese R2 DVD]
2002: Macross Zero [Japanese R2 DVD]
2008: Macross Frontier [Japanese R2 DVD / Blu-Ray]
The bits in square brackets are the 'easiest' (legal) way to watch the series in question.
As you can see, Macross is a series that's virtually impossible to get into if you're into playing by the video company's rules. Macross Plus is literally the only thing available on UK shop-shelves, and even then, only the original series is available in English from other regions. However, a cynical side of me says that there's a very good reason for this:
Macross and Macross Plus are the only properties in this franchise that are truely worth watching. Ok, Frontier doesn't count because it remains to be seen whether western anime publishers will pick it up (I reckon they will, and it deserves it), but look at the rest of Macross and you can see why it's obscure.
DYRL and Flashback 2012 are fan-only stuff.
Macross II is the one anime product that isn't considered 'authentic' Macross.
Macross Seven is, and I try to say this as fairly as possible so i'll go with an obscure pun that you'd have to be ashamed to get, utter
Trash and was an indication of how completely too far invested in the 'Culture can stop all war!' message the banal
Macross Zero would become. I've tried to soldier through 7 to no avail. It's Macross' answer to ZZ Gundam: Formulaic, poorly animated episodes that go nowhere fast and cheapen the franchise as a whole. Ok, it's not quite as bad as ZZ Gundam.
The good news is that no Macross series is so connected to another that you can't skip it, or skip straight to it. The Macross 7 properties function as a complete unit: no character from it has appeared in later series, though it does have several characters from SDF Macross present. Macross Zero has one character from the original series in a supporting role (it's a prequel). Macross Frontier has yet to contain anything beyond references to the other series.
My viewing advice? SDF Macross > Macross Plus > Macross Frontier. (If it gets released or, you know. Ahem.) Watch the rest if you have time to kill.
As for the Robotech version, watch it only if you are curious about the antiquated 'rip it up and piece it together for an international audience' approach to anime localisation. Robotech is also arguably the reason why there is no Macross in the UK as there has been a long history of legal battles over how Macross can be released and it's probably simply not worth the hassle Harmony Gold will give you for undermining yet another of their one episode attempts at reviving their eighties one hit wonder.