Why we can add maximum 50 email account on domains.live.com ? What can we do for add more accounts on us domain ?

and a bonus question;

We are a big company. We use 124 email accounts. We dont want to any problem for email accounts or if we have a problem we must handle quickly and exactly. we research domains.live.com admin panel and we saw limited options. for example we can just 50 email accounts per domain or we cant change passwords. 

So here is the bonus question, what can we do for full control on admin panel ? 

Thanks.