Norse, no other option from Europeans is reasonable unless you go into Pytheas of Massalia PODs which I did try a TL on (It didn't get very far though and I was pretty unsatisfied with the results).
Calling all Norse 'vikings' I find would be like calling Native Americans 'Indians'. I mean, would you go up to a sailor in the early 18th century Caribbean and call him a Pirate?
Would the Norse of Vinland be able to accomplish this
If the Norse were willing to mass colonize a frozen hell-hole like Iceland then the extra distance will pay off, they won't get many colonists from Norway and such but they will from Greenland and Iceland.
I'm assuming a more successful Viking colonization leads to other groups attempting to colonize
Not for a long time.
The only people sponsoring and organizing colonizing it are going to be people relatively close by(Iceland/Greenland). The only ones with the Technology to even get there would be the Scandinavian countries and maybe England, even then it's hard. Canute's empire was struggling from just the distance between England and Denmark so going along the North Altantic is a no go for European Countries. Maybe Some exiled noble who goes to Iceland tries to build something in Vinland but there is little else.
resulting in proper settlement of, apart of Norse, Germanic-Latin population.
How will they get there? Even the Norse had trouble in Polar waters and only those born near the poles and experienced with them could navigate safely. Also any continentals would have little reason to, undeveloped land was becoming rarer but not overly rare.
I think you may be underestimating how quickly a colony could grow in terms of natural increase.
This. Assuming a couple has six surviving children (I think thats the average at the time correct me if I'm wrong.) then thats a multiplication of three for each generation, combine those numbers with slaves, assimilated Skraelings, and fresh immigrants then it will gain traction very fast.
First Viking to Columbus is half a millennium.
Plenty of time to grow into a World Power
I figured maybe starting on an island could work.
I did this in my TL (Shameless advertising) the Magdalene Islands are something that very few people take into consideration.
good start for further expansion down the coast
Ehhhh... I think the Norse would confine themselves to the St.Lawrence gulf given the risks of higher Skraeling population to the south as well as winds and water currents that will try and blow you into the middle of the Atlantic.
The Vikings will have the huge advantage of diseases decimating the locals
when Smallpox makes its way it will still decimate a whole lot of Natives. Also for a more recent epidemic the plague that killed Eric the Red could work.