1 I have been loving you so much. I have been in love with you so much.
- They both sound a bit odd, If you are using so much to express time you could say " I have been in love with you for a long time"
2 I quit the club. I am quitting the club.
They are both grammatically correct just different tenses
" I quit the club" means that the action (quitting) has already been done
"I am quitting the club" means the speaker intends to quit but has not yet done so
3 Let’s go to his home. Let’s go to his house.
Both make sense in English, however the term home sounds more polite. Either would work :)