j13ntv; Hi! In order:
(1) The small tank is called a header tank and is sometimes used to give longer flight times,or move the tank back to where you can see you fuel level and some people use them to help when they start flying the helo inverted, this "header tank" will (if plumbed properly) stay full of fuel no matter how hard you throw the helo around!
(2) The clutch system on you helo is like a mini bike clutch...the engine starts and idles too slow (if the throttle is set correctly) to turn the main rotor..never the less you must ALWAYS hold the main rotor by the blade grips while starting the helo! Remember...this is NOT an OSHA approved devise!
(3) There are too many things that might be wrong...some more info would help.
(P.S.) Without knowing if the engine is broken in on something else ( I'm assuming this is a previously owned bird (?) ) and other things like the type of muffler it would be hard to say what fuel to run...however, 30% nitro is very expensive to run if you are just learning to hover and fly around...15% will give you all the power you need , however, as I said, if the engine is "used" to 30% this might present some tuning problems...some more info, please!
If you are a new heli pilot, I would suggest getting a Ray's Helicopter Manual from Rick's it has ALL the answers in an easy to understand format...also the Pilot Locater may help you get hand's on help which makes the learning curve less steep and more fun! Rick's website is www.ronlund.com (I hope that wasn't against the forum rules). Have fun and keep posting, Chris