Can you trigger Gloin's response due to Landroval's repsonse?

Response: After Gloin suffers damage, add 1 resource to his resource pool for each point of damage he just suffered.

Response: After a hero card is destroyed, return Landroval to his owner's hand to put that hero back into play, with 1 damage token on it. (Limit once per game.)

This one could go either way. Given that he is entering play with a damage already on him I would guess no.

I would say no. Gloin has not "suffered" damage. In practical terms, if Gloin has been destroyed he has more than likely taken 4 damage. So being put back into play with just 1 damage could be considered damage reduction if anything!