Hey there. A few things first.
All DAWs (Digital Audio Workstations), also known as the 'recording program' are going to be a little difficult to understand if you're a complete beginner. So you'll probably have to watch some tutorials on youtube or something in the very least. Also, Apple laptops are pretty expensive, so if portability is not an issue, and recording your music is the main priority of the computer than you should just get a PC desktop for roughly the same price (and it will have a lot more power and therefore better for recording audio digitally), or maybe even an iMac which is a bit cheaper and more powerful than a Macbook Pro.
Firewire vs USB: And yes Firewire 400 or 800 interfaces tend to be better than USB, and USB 2.0 interfaces because of the higher possible transfer rate with Firewire than early USBs. The higher transfer rate means it can transfer more data quicker and will therefore have a lot less latency (will get to that later). The problem with Firewire though is that it is becoming rarer as USB 3.0 was released which is very fast. THE PROBLEM IS NO ONE IS MAKING USB 3.0 INTERFACES!!!
So if you can get your hands on a good, affordable computer with a Firewire port on the motherboard than do it. They do make Firewire cards that can be connected to non-Firewire motherboards/computers and they are rather cheap so it isn't THAT much of an issue. I'm sure someone at Bestbuy or Tiger Direct (or any computer store) could install one for you if you think it's tough.
The Audio Interface: So naturally I'm sure you realized that you will need something to actually plug in the microphone and headphones to, and then connect ultimately to the computer. This is the audio interface. These are basically external sound cards. And yes they come in either USB or Firewire connections. You'll find the Firewire ones are slightly more expensive for the reasons stated above, but they are definitely worth it. I actually recommend beginners to buy Firewire over USB because I mentioned something called 'latency' which USB interfaces are more prone to. Latency means that there is a delay between what you are playing and recording and what you'll actually be hearing coming back from the computer. So lets say you recorded your drums and now you want to play along and record your guitar overdubbed on top of it. Well, if the soundcard and audio drivers (programs that sync soundcards to your operating system) are bad and have a lot of latency you will find it very difficult to ignore and will make everything sound off timing. You'll experience latency with all interfaces but good ones can get it down to about 5-10ms which is not noticeable at all. I recommend Presonus Firewire interfaces for PC like the Firestudio Mobile which costs around $300, and Apogee for Macs - even though the Apogees are USB they are designed specifically for Apple so they work very well and have very little bad latency.
DAW (recording program): You're familiar with Logic and you said it was hard to use, but was it Logic Express or some other version of Logic? Unfortunately, either way, Logic is actually considered to be relatively 'simple and easy to use' in the world of DAWs so if you're having trouble with that than others may be really difficult for you
. Logic of course is only compatible with Macs. There are other entry level DAWs for around $99-249 like Steinberg Cubase Elements 6, and Cakewalk Sonar X2 Essentials. The former is compatible with both PCs and Macs, and the latter is only compatible with PC. These are my favourite entry level DAWs personally but look around. Someone mentioned Reaper which is great for beginner type stuff, but you mentioned you wanted to add synths and digital instruments, and Reaper isn't nearly as good at that as DAWs like Cubase, Sonar, Logic etc, are. Another thing, if you buy a new computer and DAW, make sure the operating system is a 64-bit version and same with the DAW! 64-bit OSs and programs are becoming the standard and will be much more 'future-proof' than 32-bit ones. To be honest I don't even know if they actually still sell 32-bit Windows 7 at chains, but they definitely still try and sell a lot of 32-bit version DAWs - don't buy them.
The Computer: Whether it's an Apple or PC, laptop or desktop, just make sure it has:
1) An ATX motherboard
2) A good 64 bit operating system. I recommend Windows 7 Home Premium 64 Bit edition for PC, or whatever the latest OS X is for Apple (they are all 64 bit).
3) A lot of ram! 4GB and over is desirable. Speed/frequency (MHz) of the ram doesn't really matter, just make sure it has a high amount of memory (high gigabyte number). Luckily ram is also rather cheap.
4) A good CPU! I use the Intel Sandy Bridge 2500K personally. Great for the money. If you get an Intel Sandy Bridge, or Ivy Bridge processor make sure the motherboard is an LGA1155 socket type!
5) A hard drive with lots of space! The higher the RPM the better. I use a solid state drive. They are even much faster than regular hard drives but they tend to have less space to price ratio. A good SATA 3 6.0gbs solid state drive costs around $150-$200 for 256GBs.
At the end of the day it's cheaper to buy all of these parts separately than to buy a prebuilt computer from Dell, HP, or Apple, just make sure you have someone who knows how to build computers. It isn't really that hard so ask around, maybe someone in your area can do it for cheap.
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) coupled with audio interfaces.