Ya you could just focus on chins. Or some pulldowns + add some pullovers. These 2 types of exercises should be part of your back routine anyway.
As far as rows, do something like in the pics; like hammer rows they're actually more intense on the lats IMO. On the first one you can also use DBs if you like.
As far as the chest issue, you can move up or down the bench to avoid it; the back will still be braced. Or lie perpendicular to the bench; as long as the back's braced somewhere it'll work. You can use a towel between the bench and you it should help a little.
One-arm DB rows; again because the back's braced i find them more effective than two-handed rows, and less stressful on the back.