mutter to oneself. - Past sentence. <--Muttering to oneself - Past sentence is a better use of the tenses.

Today was rainy and hard windy. <--You can use very windy since its better for description.

I went to school.I took a bus and train.It's takes about 45 minutes. <---It took around 45 minutes is what you should be using since it is something that happened.

I finished school at 2:15.and then I returned my home. <-I finished school at 2.15 and then returned home. Both sentence can be used together since it describes one continuous action.

I studyed English at home for about five hours. <--I studied English at home for five hours. Since you have specific number you dont have to use "for about".

ごめねちょっとむずかしい。