I have been commuting for about three years. I gone through several rims by wearing the rim down from braking. I decided to go with disc brakes in front since I use the front brake the most and I don't have a disc frame anyway. I can buy a fork for my Surly 1x1 made by Surly or a similar fork that is disc only made by Dimension. The Dimension for is a little cheaper. I've also decided on Avid bb-7 brakes due to simplicity and quality.

Here are the questions:

What size rotor should I go with? I think I'll need more that the standard 160mm since the bike is heavily loaded sometimes. Will 185mm be enough and will 203mm be better or overkill?

The Dimension fork is disc only. The Surly fork is disc or canti mount with removable bosses. The Surly fork is slightly more expensive. The Dimension fork will have a nice clean appearance with no canti mounts. Any thoughts on the two forks, quality or performance wise?

Am I overlooking anything on this front disc brake conversion project?
The best prices I've found for the brakes is $54 for the 203 rotor and $64 for the 185mm rotor.
$65 for the Surly fork and $52 for the Dimension fork.

If I understand things, if I wanted to go to a different size rotor, all I would have to do is buy the adapter and rotor. Those two items would make the change over, correct?

Thanks a lot y'all.