I suppose if we don't mention particulars or anything, it would be spoiler-safe. At least we can try. Oh, yes, this is a post with a tad more serious intent than the other one.

So, the issue - I noticed, on another thread, a scant mention of a thing that, er, was slightly worrisome. As in, it implied that you needed to be within a 'faction' to do some of Dragonborn's content.
So, to those that know - is that generally the case, and if yes, could you please mention which factions, or which quest-points of Skyrim's plotlines you need to have in order to not miss out on Solstheim stuff? Thanks in advance.

Ed.: Ofc you don't need to say "to do XYZ and unlock DJHS and get the approval of SFH you need to be in the Wuss-kicking College of Incendiary Awesomesauce.", all I kinda want is along the lines of "Well, dragonborn has some stuff where you need to be, say, accepted in the College of Whispers."

You can travel to Solstheim at any time and do all the sidequests including without any experience in Skyrim, just so long as you can pay for transport.

However, you must have finished up to "The Horn of Jurgen Wind-Caller" in Skyrim to do Dragonborn's Main Quest.

At least that's how I understand it.

The only optional content that's dependent on progress in a particular faction would be the You don't need anything aside from that, but additional dialogue lines are possible.