Overall info: speaker, electrical engine, IR.

Hello.

Today I demounted some old RC car. And I've got some parts, but I'm fairly new in electronics so I have few questions.

1st question:
why this engine has stuff on it? http://i.imgur.com/SDQKl4y.jpg
I'm assuming that 1 is capacitor, and 2 is diode. Can't just I desolder it all and just give resistor to the circuit? Or do I have to give an extra capacitor for it? What are the best voltages etc. for this kind of engines?

2nd:
how to speaker? http://i.imgur.com/HDASjSY.jpg
I've got this speaker, does it work like normal piezo buzzer?
Edit: on the back of speaker there is some info:
http://i.imgur.com/TWR14yL.jpg
F J, 8? , 0.25W/(V?)

3nd:
That IR (is it IR?) stuff http://i.imgur.com/2mT2RqM.jpg
Can I make something useful from this?

Also there were 3 transistors:

Is there any difference between them? Or stuff that I need to know about them?

Well, sorry for newbies questions.

The caps on the motor are for RFI suppression.
Can’t make out the other components (posting from phone)

No, that’s a standard voice-coil speaker, and no, it doesn’t act like a piezo buzzer.
Don’t connect it directly to an Arduino pin.

The IR device is probably a 38kHz detector/demodulator - yes you can do useful stuff with it, probably stuff like decode IR remotes, with appropriate software - check out Ken Shirriff’s (hope I got the spelling right) library.