If you are traveling by air to leh one day rest is recommended before you start your adventure as your body needs to settle in high altitude. Though the journey by road from Manali to leh or Srinagar to leh will automatically mix you up with the conditions but not for everyone, even army doctors recommend one day rest. Accurate mountains sickness AMS is real don't take chances.
Inner line permit would be required for visiting some place which can be obtained online using this link http://lahdclehpermit.in/ , For making payment you have to take printout of the application and reach
Leh TIC Office, Opposite J&K Bank
Main Market, Leh.
Taxi Traveller drivers will take permit themselves.
List of places which requires inner line permit are Nubra valley, Khardung La, Pangong Tso, Tso Moriri, Dah, Hanu Villages, Man, Merak, Nyoma, Loma Bend, Turtuk, Tyakshi, Chusul, Hanle, Digger La, Tangyar (for trekking only). Make sure you get permit one day before you start adventure.