Kinda did this backward - oh well...
I am prepared to spend if i can get it going. Actually i might go down the hobby store and look and ask some questions. I am from sunny Australia so most of the stuff I have to get online or improvise (actually improvise a lot because I want to get this working so I can justify the purchase of more. )
A quality electric R/C truck (no radio or such), such as a Traxxas will run you around $400.00 USD; just keep that in mind - it isn't a cheap hobby (and combining that with robotics - well, if you have the money - have fun!).
The battery on this car is a 9.6 volt, 750mA NiCd rechargeable. Honestly I am amazed the car came with it at the price. I did measure the voltage, but I can't see it in my notes which probably means I wrote it on a post it note(yeah smart I know)(edit: about 3.5, but it was really hard to measure cause I just had to stick the multimeter in while holding it on which is hard to do without a third hand. I figured holding control in palm still allowed me to hold the probe off multimeter), so I will look it up.
In the future - don't do this; this is bad practice. Instead, solder wires and/or use alligator clips to attach your probes to the circuit in question where you want to measure, with the power OFF. Double check all of your work, make sure nothing it inadvertently shorted, and that you have your probes connected exactly where you want them, and that your meter is set up properly. Then carefully turn the power on, and keep your hands off the probes. Live probing should never really be done, unless there is no choice (and you set things up like I told you to earlier with wires and such); get into this habit. Had this been a high-voltage/high-current circuit, bad things could happen. Learn now, get used to it now, and you may save your life later.
Could you explain what TTL equivlent is? (I would rather understand than just do).
This is from wikipedia (http://en.wikipedia.org/wiki/Transistor%E2%80%93transistor_logic
"Standard TTL circuits operate with a 5-volt power supply. A TTL input signal is defined as "low" when between 0 V and 0.8 V with respect to the ground terminal, and "high" when between 2.2 V and 5 V (precise logic levels vary slightly between sub-types and by temperature). TTL outputs are typically restricted to narrower limits of between 0 V and 0.4 V for a "low" and between 2.6 V and 5 V for a "high", providing 0.4V of noise immunity."
Currently I am using a 9 volt clip battery for arduino, but I have read the wifi shield I have needs a fair amount of juice and I plan to hook an array of sensors up to it.
A couple things - that battery has enough voltage to run your Arduino via the barrel jack, which is OK for now, but I would do something different about the battery. It has a fairly low "run level" - that is, a battery is measured in amp-hours (AH) - that is, a 1 amp-hour battery can supply 1 amp for one hour (or 500 mA for 2 hours, or 2 amps for .5 hours - see how that works? In practice, you'll never see these numbers in real life, but that's the idea - I won't elaborate here on why). Your's is smaller than 1 amp-hour, though - a larger battery will be better.
Look at hobby shops and the like for 9.6 VDC R/C packs - NiMH are a good option, but LiPo packs are starting to become popular as well (just be aware that such packs, while lightweight, pack a helluva punch - there are videos online of what can happen if they should be accidentally shorted, or overcharged - though I think with a proper charger you should be OK); get something around 2-3 AH (2000-3000 mAH). That way you'll have a longer run-time for the car, with the Arduino and anything else you add.
The next step would be to bypass the 5V regulator on the Arduino (it wastes a lot of power as heat, being a linear device), but I would save that for your real R/C truck; for that, you can use a 5V BEC (Battery Eliminator Circuit) - do some research on these, they are basically switch-mode DC-DC converters, to efficiently take the voltage of the battery down to the level needed by an R/C receiver (but you'll power the Arduino with its output).
Oh - something else to keep in mind: In the R/C world, the battery may have a different connector that what you have on your current R/C truck - so you may have to do some improvisation here, too (and, you'll need to parallel the barrel connector in some manner as well; the best way would be to solder it to the PCB - trace the battery connections on the PCB, and find a convenient solder point for power and ground).
I currently don't have a solder sucker, although i might be able to find one to borrow. Is it possible to do it without the sucker?
You could try solder wick, but really, your toolkit should have a solder sucker -and- solder wick (I actually have a plunger-type solder sucker, a bulb-type solder sucker, and solder wick of various types - but I've been playing with electronics for a couple of decades now). Sometimes one works better than the other in certain cases; generally the solder sucker is good for the bulk of the work, and the wick for final cleanup of any extra.
How do I sever the antenna? It is clearly marked on the board so easy to find.
It's not just the antenna - you have to sever the power to the RF circuit. You'll need to trace the battery positive and/or the ground to the circuit, and this may take making a rough schematic (while comparing it to the datasheet's example schematic for that portion - which was located in the upper-left part of the schematic); it may or may not be easy to do. It may take some time. Ultimately, it might not even be worth it for this stage of the project (it likely doesn't consume very much power, and if you upgrade the battery pack, it won't make that large of a difference anyhow).
I already figured I can't turn back and forward on and will write my if statements so it always switches the other one off before starting as a failsafe.
Well - the thing is, on some h-bridge designs you can; it allows you to set the motor in "brake" vs "freewheel" mode - but it is a good design in your code to do these checks; put them in functions, that way you don't have to worry about them, and can just call the function you need, and you'll know it works (for that matter, put the "set all outputs LOW" in a function as well - call it something like "initOutputs()" - then call that function from setup(), before loop() is entered).
Something I forgot to mention in the last post, in regards to cutting traces: To cut a trace, you can either scrape the copper away with a hobby knife (x-acto or similar), or use a dremel-type tool with a diamond point burr cutter or similar. Just remove enough of the trace so you see the PCB material underneath, leaving about a 1-2 mm gap.