Yes, you can, the main thing is to have a template recognizable by the primers to validate your pcr, and also to have a previously known size mark on the agarose gel (ladder verified).

It depends what experiment you are controlling. If it is to check that a restriction enzyme is working for a site in your amplimer then yes. As a control for the pcr amplification then it is not ideal because unless it is hugely diluted it will amplify perfectly and over amplify compared with the real samples and you will just have a smear of amplified material not a band. If you know that you will run out of control sample then just collect the raw material from many samples that test positive ,mix them and test this mixed material as the new control sample while you still have some of your original control

Dear Malik Gawharul Haq

It is always better do positive control with each experimental setup unless you are so confident in setting up the reaction. Sometimes the experiment itself does'nt work due to human error where you can refer positive control if the same didn't amplify you can conclude that there is some issue with the experiment. But this conclusion can't be made in your case where positive control made as stock and used for following experiments.