das, in addition to the aforementioned rebel group list, could you tell me which colonies changed hands during and after the Fifty Years War? I'd like to know which areas have English/French/Flemish minority populations.
Your two questions are not as closely connected as you seem to think they are; there have been other migrations unconnected to the colonial race and there have been colonies that have been more or less wholly assimilated or, more likely, simply overran. There are, ofcourse, Flemings and Frenchmen in the more southerly parts of the Arcadian Atlantic seaboard and Flemings and Portuguese in the Argentine; New Leon is populated mainly by Galicians; and the north of south America is an uncertain hodgepodge with German settlements in Portuguese territory and vice versa. There be Englishmen and Portuguese in Brasil. No other truly notable things except maybe for the "Venetian" quarters in many Indian Ocean cities (those house the "pure" descendants of Venetian merchants and soldiers, the metises and various non-Italian people who are nonetheless "Venetian" culturally; though this "Venetian" culture has, to a great extent, gone native over the centuries, not in the terms of religion, but in the terms of nearly everything else). I suppose there are some Englishmen - or, more likely, metises - in Japanese America, though not in the larger coastal towns; the Japanese massacring policy has been relatively relaxed there, but still.
a small list of important ATL individuals and their nationalities
How important is important? There were a lot of those people. And you do probably realise that a simple "small list" won't suffice; they were all important for
something... Meh, I'll see what I can do.
a list of rebel groups and movements
Going over the major groups, there is a growing republican-arbeitist underground in Arcadia itself, a "Mexica" native revivalist movement (you can guess where), colonial separatists in German Orinoco, anti-isolationist groups in coastal cities and border communities of Tawantinsuyu (it's not so much an ideological matter as a matter of them being already involved in illegal trade with foreigners and so both in trouble with the authorities and eager to make their lives easier; the fact that many of them are united by something of an unusually sophisticated and wide-reaching cargo cult makes things worse, ofcourse), Brasilian colonial separatists mixed with arbeitists, collective British and separate Scottish separatist organisations, Young Gaul reformers among French officerhood and educated bureaucracy, Catholic reunionists within the Avignon Church, Castillian, Leonese and Morisque/Mozarabic separatists, a more centralised arbeitist movement in Flanders and the HRE, Danish "republican" (of the ends justify the means, the will of the People's Republic could be represented by a small heroic vanguard that answers to no-one and does whatever
it wants is necessary variety) ultranationalists, a nationalist-arbeitist Italian movement, Czech separatists, Polish and Hungarian nationalists, Lithuanian clan-based malcontents, Volga Bulgar nationalists, Wallachian nationalists, Bulgarian regional and national separatists, Greek separatists (in Greece Proper), ultraconservative ludditesque privileged peasantry and old urban mercantile corporations in Chernigov, various tribal malcontents throughout Africa, the more organised semi-autonomous Beninese court currently presided over by an ambitious and independence-minded king, Muslim tribe-based rebellion-minded confederacies in western and eastern Ethiopia and southern Egypt, Cyreneican French-descended Avignonists, a few splinter highly radical Ismailite sects in Egypt itself, pro-Jadfdi Arabic tribal groups all over Egypt's eastern frontier, Jewish Zionist nationalists (not very violent as yet, but this might change as this gains speed; divided into secularist and millenialist branches, the sub-branches of the latter already having certain candidates in mind), Angoran Turks in the border regions of all neighbouring countries, Sunni Turkish groups in Iraq, Parsi (technically an uncertain majority) and other non-Turkish tribal groups in Iran, tribal malcontents in the Golden Horde (especially among the northern and northeastern tribes for some reason), provincial separatist governors (in the west; strongly pro-Tverian, so if the Golden Horde tries to crack down on ties with Tver it will likely have a rebellion on its hands), Rajput principal autonomists/separatists, Muslim Turkish and Mongol groups in Punjab, Gujarati nationalists, anti-Malla pro-Bengali Indian rebels, regional anti-Bengali separatists (especially in Burma but also in central India), regional Indochinese separatists, anti-Portuguese traditionalists in Siam itself (also, at the royal court), pro-Xin Ming Chinese peasant secret societies in all non-Xin Ming China, the White Lotus Society (technically pro-Xin Ming, but might break away any moment now as there have been strong disagreements over the recent reforms among other things), Manchurian tribal and aristocratic traditionalists, Korean separatists, Japanese "Westernisers" and re-isolationists, the Oomoto sect (no relation to the OTL sect; rather, an anti-feudal anti-Shogunate Pure Land Buddhist-Christian syncretistic sect with messianic pretensions, increasingly widespread among the urban underclass in the Home Islands), the Javanese nationalists, the (Catholicised, but much more numerous than in OTL) Maori monarchist separatists. Those are the major groups, for now.
Now go and sort that out.
Arbeit means "work" in German, "Arbeitist" is just a generic Anglicized term for a workers' movement. 
