1. is it ok for him to stay in his hide all day?
Yes, and make sure you have a hide on the hot side and cool side, very important with babies.
2. When I feed him how long should I wait to handle him?
I would give him a day or two to let it digest, remember snakes are cold blooded so the it takes time for them to break down their food and if there is too much activity before it is broken down it is going to come back up. Not trying to scare you but in a full day or two it should be fine.
3. Is it anyways to tell how old he is?
Size can help give you an idea of the age however if the seller didn't or know or didn't tell you it is very hard to say some people over feed their snakes with makes them bigger faster but a lot of people also under feed their snakes (petstore do this all the time) simply to keep them alive.
4. Im using a clip lamp with a red bulb, is that fine to use for a heat source..
I will be honest I personally would return the heat lamp and bulb and just go with uth (under tank heat), get a heating pad that is right size for you cage set up. Most snakes in the wild go out on road or rocks at night to get heat from the ground they don't tend to clime up and bask in the sun. Side note heat rocks- BIG NO NO, don't get one just get a uth and you should be fine.
Good luck and hope you enjoy your new friend!!!
matt