Leopard Tortoise Babies

Question
Hello! I have 2 Leopard Tortoise babies, around 6 weeks old. The smaller one is very active and he/she is making these light chirping noises. It seems to be extremely vocal. The larger of the two is much slower and doesn't make any noise but it eats so much more and has regular bowel movements. They are in an outdoor enclosure as I've been told that is the best environment for them as natural sunlight is the best for their health. I bring them in at night because I feel it is too cold outside.
My Questions: They have Timothy Oat Grass available at all times to eat but will not take a bite of it. They simply burrow themselves in it to sleep. They have tall fescue as well but will not eat it. Right now they are practically only eating Mulberry Leaves, Dandilion Leaves and some bits of clover. Since they act so differently, do you think there something wrong with one?
How can I get them to eat some grasses
I've read a hundred pages about temperatures for them and some vary. At night, what is the lowest temp it can get to for them?
Thank you for you answers!

Answer
Temps: Be conservative for babies- I would get worried at 70, and personally not go below 65F, although I know some sources say much lower.

The things they are eating are actually pretty good. I'd not worry about his a lot, but you can find good things to plant on sites like http://www.sulcata-station.org or http://www.tortoisetrust.org to try as well.

You do not say anything about it, but make sure they have some non-grass surface to be on- too much wet grass contact can cause shell problems!