Trailer brakes help

[bigeasy1]

Well,I'm finishing up my 23 Tsunami,and now need to replace the brakes on the trailer.
I have a couple of questions for anyone who has replaced their brakes,or did a retrofit to discs.
The trailer is a Shorelander galvanized tandem axle.

I'm basically going to only make one tow trip of 400 miles to get the boat to the lake.After that it will be only to the launch,about 1/2 mile.

****This is fresh water great lakes use only****

* Should i convert to discs?I have to change the coupler anyway,as it's shot.
* Is their a big difference in stopping power between drums and discs?
* Is it a straight foward job to change,and are ther any common problems to look out for when doing it?.

The trailer is in extremely good shape,but was left sitting in a field for about five years,someone bent the coupler,so i figure now would be the time to put a new one on,for discs,along with the free backing solenoid.
I know the lines look pretty rusted,and the bleeder valves look like they are not coming loose to easily,so i feel that's a good reason to make the changeover.

Any advice, comments,or opinions would be appreciated.Thanks all.