Advises for redirects

[Tit]

I worked on a website since 2 years now (mainly link building). Now, I need to change the CMS and the hosting company of this website. In order to improve the SEO of this website, I decided to change the URL structure as well, see example here below:

Actual situation:

http://www.mywebsite.com 
http://walla.mywebsite.com/ 
http://ortak.mywebsite.com/

http://www.mywebsite.com/de 
http://walla.mywebsite.com/de 
http://ortak.mywebsite.com/de

http://www.mywebsite.com/es 
http://walla.mywebsite.com/es 
http://ortak.mywebsite.com/es

Future situation:

http://www.mywebsite.com 
http://www.mywebsite.com/walla 
http://www.mywebsite.com/ortak

http://www.mywebsite.com/es 
http://www.mywebsite.com/es/walla 
http://www.mywebsite.com/es/ortak

http://www.mywebsite.com/de 
http://www.mywebsite.com/de/walla 
http://www.mywebsite.com/de/ortak

• Since the hosting, the CMS and the URL’s will change, what you recommend me to do in order to keep a maximum of “link juice” to the pages!?

• How / Where to setup the 301 redirects?

[IKT]

To tell you the truth it is actually very easy , but you have to familiar yourself with .htaccess HTTP REWRITE engine .. Seriously it took exactly 2 lines of code to detect and 301 redirects walla.mywebsite.com into www.mywebsite.com/walla

HTTP Rewrite is an extremely useful tool, if you are not familiar with them , please go here http://www.yourhtmlsource.com/sitemanagement/urlrewriting.html (or just google http rewrite redirect)