OK, I'll answer these as though they were in my legal jurisdiction. You might want to get a consult with a trans-friendly lawyer to make sure they apply in your jurisdiction.
1.) Does one that has SRS have to change his or her name?
No, but it's a bit tricky functioning as a male with the name Priscilla. And the Benjamin standards might get in the way of SRS if you don't change your name.
2.) Do all igsisting legal papers have to be change as a result?
Most will require renewal at some point and then you will need to change them. I'm talking about ID here. Other legal papers, like diplomas, wills, that sort of thing, you don't necessarily need to change, but it does mean you have to out yourself at some point if you need the paper.
3.) Does couple married before name change have to get married all over again for it to be legal from Will stand point?
This is very jurisdiction specific. You may not be able to re-marry once one changes gender. If you live in the UK, you may be required to divorce if you change gender legally. I don't think any states require that. If you lived in Canada, it wouldn't matter because same sex marriage is legal.
From the perspective of a will, remarriage or marriage, in Canada invalidates a will, so it would not be a good thing to do unless you're rewriting your will.
In Canada, and the UK, if you wrote a will leaving your estate to "John Smith" and "John Smith" became "Jane Smith", all that Jane would have to do to maintain her status as beneficiary is to prove that she is the same person who used to be "my husband, John Smith". But you really need to check this for your jurisdiction.
4.) Does life insurance policies have to be change or does the old one still have authority and validity?
Risk factors may be affected by transition, and that could be considered a material misrepresentation much like starting smoking after you got the policy could be. On the other hand, if you told the insurer about the transition, you may find yourself not covered. Your choice, you can have a fight afterwards if they decide to be dicks about it, or you can disclose now and risk that they'll make the decision not to insure you at all. You really need to check with a local lawyer.
5.)If they are not changed by the Insured are they still legal?
Again, see above re material mispresentation. Name change is not a problem. You are still legally the same person you were before, upon presentation of a certificate or court order changing your name. You need to have legally been the person you said you were at the time you signed the insurance contract. Transition might be a problem though for medical reasons.
6.) Let's say the benificiary is the one with the SRS and name change, does the insurance company still have to pay the person that was the benificiary by name in the document but is the person by new name and gende rafter SRS?
You should be alright as a beneficiary by simply proving that at the time the contract was signed, the beneficiary was legally known as that person.
7.) Is it manditory for "Name Change"and liciences and past port and everything to be change when a body goes through SRS.
Not mandatory, but tricky to present a passport that says "Lancelot Buck Jones" and a set of knockers. And, there is the Benjamin thing. You might not be seen to be taking transition seriously if you don't go through the legal steps.
8.) IF someone is being left something in another's "Will", and the name, sex identity ect. were changed will it be awarded to the intended person as per stated in the "Will" even though that person is someone else by name now?
Will, yes, they just need to show proof that they were the person named in the will.
9.) Is the clause "this person is know by ..... or by.... a cover's all bases clause?
AKA clauses are a good idea, but if you know that someone has changed their name legally, it's best to actually put that name in there. So, if John becomes Jane, the best way to put it is "Jane Smith, formerly known as John Smith". Or just "Jane Smith". Putting "John Smith also known as Jane Smith" would only be appropriate if the person hasn't change their legal name.
The best, cover-all-bases, don't need to worry about fighting later idea is just change your name legally and then change it on all your ID, wills, powers-of-attorney, diplomas, everything. The main caution would be the transitioning person's life insurance, but be prepared, you might have a fight later if you don't disclose.
And, if I haven't said it enough times, talk to a lawyer in your area. Write out a list of questions like this (try and get someone trans friendly). Laws differ in every jurisdiction and the US laws are probably the most whacked out of all of them (sorry American list members) because of the state-centric nature of your laws and the occasional (I'm being charitable here) coopting of the legislative process by right wing Christian groups.
Dennis