The translation is correct. (Just in case, にしています means (we) have made it a rule that..)

Regarding only until 6 o'clock, it follows the basic rule of 'reversing'. That is, Japanese uses post-positions which reverses the English prepositions. So までだけ is the correct one. (If until only works in English, forget the explanation.)

Nothing should be technically wrong about 6時までだけにしています, but I feel 6 o'clock may be rather too usual to use only. Possibly it is early for owls, in which case using までだけ is fair.

The translation is correct. (Just in case, にしています means (we) have made it a rule that..)

Regarding only until 6 o'clock, it follows the basic rule of 'reversing'. That is, Japanese uses post-positions which reverses the English prepositions. So までだけ is the correct one. (If until only works in English, forget the explanation.)

Regarding できる, it sounds natural when it is talking about the speaker allowing someone to take pictures, e.g. in case of a zoo. Here it seems to refer to their own taking pictures, so 撮ったりする is correct. Note if it says that they can't take picture because it gets dark, then 見たり写真を撮ったりできるのは6時までです is correct.

Nothing should be technically wrong about 6時までだけにしています, but I feel 6 o'clock may be rather too usual to use only. Possibly it is early for owls, in which case using までだけ is fair.