Thanks for your appreciated response.
If I will apply for Tier 5 visa, I will get a sponsor certificate from Cardiff or Liverpool University, as I am going to work as a visiting research with one of academic staff there.
Now, my wife is Tier 4 student (DES),and I am a dependant on her visa, but by the end of this month, she is going to switch to Tier 2 general for 6 month, and I will be dependant on her visa as well (but the point is we will pay around £3000 as a family to renew the visa only for 6 month (the rest of her contract)). for this reason, I am thinking about Tier 5 for me to complete the 10 years.
one important question, can my wife switch into Tier 5 for two years instate of tier 2 for 6 months. as this will be longer and cheaper (£1000 for whole family). of course this will be in case her supervisor and the University will agree.
With regards ***** ***** my visa from Egypt. of course I do not like to apply for Asylum, especially I am close to apply for ILR, as far as I know apply for Asylum is very complicated case and need a lot of evidences and may take very long time.
my question here is if there is any exception to renew my visa from my home country due to the risk of persecution, or at least if I can renew from any other country outside the UK.
Again just for confirmation, Tier 5 or Tier 5 dependent could be account in 10 years long residence. is that true.
So it will be better for my wife to switch to tier 2. the point it is if she switch to tier 2 this only will be for 6 months and she can not grantee if she can extend in the future under tier 2. while on the other side, if she can switch to Tier 5 this will be for 2 years.
My last two questions:
 Now there is a 6 months rest in the contract of my wife. If my wife switch from Tier 4 (DES) to Tier 5, Can she still work a full time according to her contract. or he must to be in Tier 2?
 My question here is if there is any exception to renew my visa from my home country due to the risk of persecution, or at least if I can renew from any other country outside the UK.
Thanks for your kindly response.
In my case, Now I am Tier 4 dependent (DES), SO if I get the chance for job, so I can switch to Tier 2 general from UK.
BUT, by the end of this month, my wife may switch to
 tier 2 general, so I will be tier 2 general dependent in this case, and as I read, if I get the chance for job, so I can not switch to Tier 2 general from UK, I have to switch from outside, Is that true?
 In case. my wife switch to tier 5, then I will be tier 5 dependent. So if I get the chance for job, so I can not switch to Tier 2 general from UK, I have to switch from outside, Is that true?
Sorry the last two lines are not clear.
Do you mean that. if I have tier 2 dependent visa, and I get chance for job offer with certificate of sponsorship for tier 2 general visa, then I have to switch from outside UK, or it is not allowed to switch from tier 2 dependant visa to tier 2 general visa from inside or outside the UK.
Great, it is more clear now.
So if the get a job offer and I would like to apply for Tier 2 worker, I have to leave and apply for re-entry under tier 2.
in this case there will no any cut on my long residence (10 years) if my current visa not expiry during my new application process from outside the UK.