LiPo Battery Characteristics

When it comes to recharging a LiPo battery, do I really need a special charger? I have this battery: Polymer Lithium Ion Battery - 1000mAh - SparkFun Electronics

It comes with a built-in Protection Circuit Board; cut-off circuits that prevent over-charging (above 4.2V) and over-discharging (below 3.2V).

So the question is, if I hook this up to a 5V @ 500mA rail, shouldn't the built-in PCB prevent over charging (and thus a catastrophic fire)?

Second question is about wiring two of them up in series to get 7.4V setup.
I know I can get 2Cell PCB and remove the current PCBs (sorta like this one: Rechargeable Batteries & Battery Chargers - PCB for 7.2V Li-PO and Li-ion 18650 / 18500 7.2V battery packs (7A Limit)-PCB7.2V7A ). The 2-Cell PCB should be able to balance the current in both cells and perform the same over-charge/over-discharge protection for each cell. So do I still need a special 2Cell charger? or can I just hook the setup to a 5V@500mA rail?

Thanks.

NO.

The components you see on the battery are BASIC thermal and over/under voltage cutoff components more than likely, they're not meant to control a charge they're meant to keep people such as yourself from catching the house on fire =) If the circuitry acts as you describe in theory you could rely on a 5V 500ma rail to charge the cell safely, but again that circuitry is meant as a failsafe not as a primary charge controller, it's your house that'll burn down if you're wrong.

I'm not sure why you even asked the second question, how do you intend to charge a 7.4V battery (even at the low cutoff of 6.4V) with a 5 volt source?

Simply speaking if you don't know EXACTLY what you're doing then YES you absolutely get a proper charger.