I'm a roadie/BMXer, looking at buying an On-One Inbred SS. I've got most of the spec down, but I'm not sure about the fork and brakes.

I know smeg-all about suspension, and I don't really know what i need. I'll probably use this bike mostly for smooth-medium trails (around local forests and farmland) and bad-weather road riding (road bike doesn't have fenders y'see). I weight a fair bit, 250+ maybe, but I'm not going to push anything to any limits, I just wanna have fun getting muddy.

On-One has a deal on Fox Vanilla 125Rs, 100RLs and Float 100Rs (I think), and since money is an issue at the moment, I'm trying to get as cheap a fork as possible. The Vanilla 125R is £250 when bought with a frame, but I could probably stretch to £300.

What should I look for? Air or coil (which is better for what riding type?)? The frame is designed for 100mm travel (all three of the Foxes are adjustable), so no big 5 inchers OK? Disk ready of course, but what's the deal with mounts? I know about ISO, but doesn't Manitou have their own type? What's up with that?

Basically I want to know if the Vanilla 125R is any good, and if it's not, what is for similar money (about $400US).

As for brakes, I want a disk on the front and a V out back. I like Avid for some reason, their Mechanical disk in particular. But is it worth more money and potentially more hassle to go for juice? How easy is it to shorten lines, bleed systems etc (I like to do all my own wrenching)? As I say I'm not going to go crazy on this bike, power-wise I think hydros are more than enough. And again, what abut mounts? For the rear I was thinking Avid Single Digit 5s (and Speed Dial 5 levers, are these ok for disks?).

I appreciate any advice anyone can give me