those shields means that you have a rightful claim to that territory. So your goal is to obtain those lands by any means necessary. You also get a free CB on any nation where you have shields on.
As for Bohemia, don't bother fighting them. Even tho they are weaklings, they are also very friendly to Austrians. Your best chance is to simply vassalize the entire country and then diplomatically annex them.
Austria also has claims to Croatia (in Hungary) and Istria (Venice).
Don't attack Hungary either, it's one of the few large loyal allies you will ever find in the game that will stay friendly to you with little maintenance. Try to keep Hungary as an ally or vassal. Then diplo annex when you feel the time is right. Hungary will help keep you alive if the Ottoman Turks decide to attack you.
Early in the game, it's NOT worth it to annex or own the Hungarian provinces anyways. Their provinces are miserably poor to even bother a war with. And taking all the Hungarian provinces will give you a bunch of poor provinces that will turn into a bunch of problematic Protestants down the road. Not to mention the fact that with Hungarian lands, you now opened a huge border to Poland (they hate you) and Turkey (they hate you) and Wallachia (a Turk vassal that also hates you) and Moldavia and sometimes Crimea (usually a Turk vassal). Do you really wanna border that many enemies early in the game?
As for Venice... they are a traditional arch-enemy of Austria... I say invade them and kick their arrogant butts!!! You need to steal that CoT some day.
