only once a year do you need to change fluid if set up right or like i said if your temps start to go then some things up. but yes most of us do a flush every 6 months or so but it's really just a excuse to change other parts. which you are so have fun and just use a table,chair+bucket on chair then pop your pump off and away you go. watch rocking your case not kidding about all the cases i have killed.
stand alone molex makes bleeding a system easy as pie that's how i have been doing it now for almost 2 years because it just so easy to bleed the system with no parts in your way or if your using a "T" line getting air out is so easy.