Malaysia has a quite liberal visa policy for most nationalities with many granted 90 days entry visa free on arrival. Israelis are the notable exception as they are generally not permitted to enter Malaysia. You can see the full list at the Malaysian Ministry of Foreign Affairs website.
Note that if it is your first time arriving in Malaysia you may be finger-printed at immigration.
Malaysian tourist visas can be extended, see this story on extending a Malaysian tourist visa for more information.
All tourist entries are single entry only. The arrival and departure stamps are small, quarter page ones.
Overstays are charged at 30 ringgit per day of overstay and it is not recommended as you may be detained (and still have to pay the fine). Extend your visa rather than overstaying it.