I'm not Muslim but I know enough about Islam to answer these questions I think (I've lived among Muslims for a long time).
1.Does Islam(as an ideology taught by Muhammad) can there be religious freedom within the constituents as one of the fundamental tenets of Human rights?
Hmm, that would depend on your situation (whether you live in an Islamic country, just passing by, or not at all):
1- If you're a non Muslim who doesn't reside in an Islamic country: there's nothing you'd fear for your freedom of belief, as far as Islam is concerned, unless a fanatic Islamic government develops a super military power and decides to practice Jihad in order to spread Islam, in which case be afraid, be very afraid!!
2- If you're a non Muslim who happened to be passing by an Islamic country: just don't show any "disrespect" to the religion and you'd be safe. "Disrespect" is a stretchable word of course, so if you eat or drink publicly in Ramadan, or you put on a religious sign/symbol of another religion (a cross for example), that may be considered as "disrespect" (people are sent to jail if they are caught eating publicly during the month of Ramadan, in some Islamic countries). Some people will try to convert you but, unless you're interested, just ignore them. Calling people to the "right path" is more a less the duty of every Muslim.
3- If you're a non Muslim who resides in an Islamic country: Here we have two cases:
a- You were recognizably non Muslim from the start: for example, you were born to recognizably non Muslim parents, and you decided, or had, to live in an Islamic country. It's quite similar to the second case, except that you'd have to pay a special tax.
b- You converted from Islam or you cannot be socially recognized as a non Muslim (if you were born to Muslim parents for instance): death penalty, unless you change your mind, and go back to Islam.
The situations I presented are theoretical of course. You could get worse or better than that on the ground, depending on regions, social casts, education, generations, etc...
But my point is clear: Islamic teachings do not recognize freedom of religion, or freedom of speech outside of its tenets.
2.Why women in Islam are forced to wear veils(to cover their head or even whole body)? In a muslim countries they are forced to but in a non-islamic country, some muslim women don't wear veils. What is the punishment if they don't abide by the islamic Laws?
The veil is a bit of a problematic issue. Some Muslim scholars consider it obligatory while others don't. But it's not forced in Islamic countries at large, rather in some fundamentalist families, while other ones may simply encourage it (or not).
3.In Islam, religion, social, politics are indivisible. Does it mean mullahs and government authorities holds the same power? I believe in the separation of religion and state because without it there is no true democracy in such a country. What is your stance between religion and a state?
Well, theoretically speaking, the governor in an Islamic country must be "the emir of believers": he's supposed to be well versed in Koran and Tradition, and lead the prayers (i.e. be an Imam). But this is mostly untrue nowadays, though, as you said, religion, social matters and politics are inseparable in Islam, which is why religion can intervene everywhere.