Yes. Holland makes up 13 % of the area of the Netherlands and has 37 % of its population. That's a lot, but not enough to make the two interchangeable. Although in this sentence it's actually more correct than in general, since Holland has most of the coastline (depending on how you measure this).
It's explained at http://taaladvies.net/taal/advies/vraag/1339/ . Apparently, both forms are correct, with veel being the neutral form and vele more formal or stressed. This makes sense under the assumption that vele is the earlier form and veel the more progressive one. Proverbs are slower to change, so "Vele handen maken licht werk" is still the standard formulation.
The source also describes a difference of meaning between veel and vele that corresponds to the different uses of viel (singular) and viele (plural) in German.
I know, the R is tricky, and for speakers of certain languages it's even trickier. I won't try to explain you how to pronounce the R, because I'll only end up confusing you. I'll just say that the way you pronounce the R varies a lot from one region to another (and sometimes even from one speaker to another!): in certain areas, it sounds a bit like the Spanish 'soft' R, in other areas if the R is at the beginning of a word it sounds a bit like the German R, and if it's at the end it sounds more like the English R... You get the idea ;)
In any case, I'll leave you the link to a pronunciation course developed by the Universiteit van Groningen. Yes, the woman explains everything in Dutch, but don't worry, you'll get it -especially since I see you're on level 25 ;)
That's one of the videos about the R (they have three, I think) - and this is the link to the entire playlist: https://www.youtube.com/watch?v=YYjx9Jepu1w&list=PLF-qJ8Ed0qHcQpMyDL8Zi2G3PdQ0AoAu0 (hopefully I copied the links properly!).
Hope this helps :)