as for landscape shots, would you personally use your kit lens or 50mm? actually, do you think your 18-55mm is good enough for a zoom lens? because mine is 18-135mm and its quite heavy for me so I'm thinking of switching it to maybe 18-55mm. but I'm not sure if it's good enough?

It depends whether the landscape you want to take is close or near. I took Mt Fuji with my 50mm lens but if I was nearer to a landscape, I would use the 18-55mm. Yes, 18-55mm is definitely good enough for a zoom lens! At least for travelling, that is. I didn't really zoom in on anything when I was using my 18-55mm. I myself have another kit lens that's 55-250mm and I have only used it once at a zoo. So yeah, I think 18-55mm works well enough!