I got a 2007 Jamis Cross Country last summer, to try biking out and see if I liked it and well I getting more into it now and want to do some upgrades. I was looking at upgrading atleast the fork and and front derailer since I have to keep adjusting it and getting clip less pedals and shoes. Keep in mind that this is only a $400 bike so I don't won't to go crazy with the prices but I do want to upgrade my current components.
Any suggestions?
I was looking at these does any one have an opinion or know if they will work with my bike?

Rock Shox Dart 3 Fork '07
Dart delivers performance that's quite a bit higher than it's entry-level price might imply. You get TurnKey oil damping with lockout,
and a 6061-T6 aluminum crown.

* 4130 chromoly stanchions + 1-piece magnesium lowers
* Available with or without Poploc lockout
* Features adjustable spring preload
* Standard 1 1/8" threadless steerer
* Accepts both linear pull (V-brakes) and 74mm post mount disc brake calipers with 160mm rotor
* 4.83 lbs


Not sure if that shock will fit my current disc brakes?

Shimano PD-M520 Pedal

An incredible value in an offroad clipless pedal from Shimano. The M520 features adjustable release tension and includes a set of SH51 SPD cleats with 4 degrees of float. These pedals will serve you well and won't break the bank. Dual sided mechanism lets you easily click in without looking down at your shoes.

Compatible with shoes drilled with SPD compatible drilling.
Weight: 370 grams (weight does not include cleats)
Float: 4 degrees
Material: aluminum


Shimano SH-MT31 MTB Shoe

multi-purpose shoe from Shimano, this one is designed to work for commuting, road, or casual off-road cycling.

* Traditional lace-up design with a lace keeper loop
* EVA midsole and rubber sole for durability
* Accepts Shimano SPD and compatible clipless cleats (Time ATAC, Eggbeater, etc)


661 Expert Shoe/Eggbeater C Pedal Combo


I have no clue about derailers

Thanks in advance for your help!