3 Domains - 1 Installation - Issues

Ok guys so here is what I am running into now.

I have 1 installation originally installed using domain, abc.com

I have 3 domains, abc.com - abcd.com - adcde.com pointing to the installation.

Two Issues:

First client comes to me and says now they want the main domain to be abcd.com, so when someone types in abc or abcde they should 301 redirect to abcd.com, this is an htaccess issue I assume, any help is appreciated.

Second problem is I notice if you load abcd.com, all links point to abc.com, unless I clear the cash then its whatever domain I load first, meaning after cache is cleared if I load abcde.com first, all links point to abcde.com.

Can someone help me have modx load one domain with one set of links no matter which domain I load? And I want to choose which domain it always loads regardless of whats typed in.