It depend on your feeling,But some people (especial for young girl) ,they want be let other feel cute or friendly, they would using this. and this habit is similar with Japanese.

Oh~ this is question is really hard to answer , I took a over view on this http://www.zhongwen.com/x/guopu.htm, it is so complexe. Some characters have different tones, but In most of case we using light tone is enough,In I think everyone would be understand what you mean.e.g 聽 we always say "ㄊ一ㄥ" ,nobody say "ㄊ一ㄥˋ". different tones cases is easy. the most complex case is one characters with different pronunciation, In different case and meaning must using different pronunciation, and In real cases you will see that very often in Chinese ,espicially in Simple Chinese. So in one characters with different pronunciation,I can not give you a good answer, becuase it do not have the right answer, it depend on which character with it's own answer. If you want to learn them ,you must have more oral practice.

而且每天我每天跑步 <== 而且 this meaning is the same with "and" ,So if you want to using this sentence,it need another sentence before it. 我每天都要跑步 <== this sentence mean "I need to have a jogging everyday" ,it emphasize "need". So,If you want to say that jogging is your daily job, You may using 我每天跑步 is enough. therefor, the right answer depend on the situation.