Okay...you didn't mention Cubase, the MXL condenser or the Firebox before. You have the basis to get started right there. Grab the condenser, put it on a stand, and start recording slamming doors, dropping pots and pans and the next heavy rain out your back door and have a play. You'll soon work out what you're happy with and what you want to change.
Personally, I use Adobe Audition for my stuff...it's an effective sound editor with a good range of built in effects to play with the sound. The "Power Tools" you mention is likely "Pro Tools" which is in use in a lot of professional studios. I used to use that at work, but chose to have Audition at home because I liked it better when I didn't need to worry about exchanging files with other studios.
For microphones, I have a range but the two or three most useful for sound effects are a short shotgun, a small diaphragm condenser and a large diaphragm condenser. Probably the must useful would be the short shotgun and one that works well without breaking the bank would be
a Rode NTG2. (It's the same mic as an
NTG1 but with an internal battery compartment allowing you to use it when you don't have a source of phantom power). My main mic used to be a Sennheiser 416 but the Rode was my back up and I found I could use them pretty interchangeably. To field record properly, don't forget a fishpole and a good wind gag like a Rycote.
For recorders, the Fostex is a very nice unit--but also have a look at the Zoom H2 or H4. Especially with extra mics they do a very nice job for a good price--and, at a pinch, can do nice stereo with the built in mics. Most sound effects are okay in mono...but for the P51 flypast or the steam train, you may want stereo!
However, I wouldn't dash out and spend any money until you have a good time experimenting with what you already have!