I dont think the ER10's are causing your problems (yet) * See below. It sounds you may have charging circuit problems (very common on these bikes) and have flooded the engine by improper starting technique. (very easy to do)
You need to fully test the bike before you start trying to fix things.
Until you know exactly what is / isn't working it isn't good to second guess things.
The bike needs fuel air and a spark to run the engine (it also needs ignitiona and valve timing to be correct but since these are fixed and you don't have a camchain to go slack we can ignore these for now as the bike does run partially)
So lets break it down further.
Fuel and Air:
When the engine is turned over the pistons suck in air through the airbox, this goes through the carbs were it gets mixed with fine amount of petrol to create a fuel air mix.
Fuel burns best at a proper mixture ratio. So you need to make sure your airbox is standard and your airfilter is standard and in place and clean.
Then you need to make sure the carbs are setup properly. They have different parts in them and they are easy to mix parts up.
Cammo has an excellent carb check / setup guide that will cover all of the above
Valve clearances
The carbs are connected to the INLET side of the engine and the exhaust is connected to the OUTLET side of the engine. When the engine is running valves get opened on the inlet side to let the petrol air mix in. They close and the petrol is burned.
The OUTLET valves then open to let the burned gasses out of the engine and the process repeats.
Because engines get hot, and metal expands when the engine heats up there are clearances (very small gaps) between the valve and the camshaft which opens the valve.
Due to engine wear the valves move and the gap becomes less so the clearance needs to be re-adjusted else the valves dont open enough or stay open too long depending on how it wears.
If they dont open close properly the fuel mixture can't get in and out and it makes the engine starting bad / runnign bad.
There is a valve clearance guide on here with pictures. check these when checking over the carbs.
electrical system
you need a good battery. charge it up fully with a motorycycle charger and leave it off the bike a few days and then reconect it and try and start the bike, if it doesn't the battery has been destroyed and is loosing too much charge internally.
Normally the battery provides power to start the bike and run the electrical items when the bike is idling.
when the bike is running above idle the generator provides enough power to run the electrics and re-charge the battery.
the power from the generator is much more than than the battery power so it is reduced by a 'reg-rec' (regulating rectifier)
These reg-rec's are prone to failure on the vfr... many people fit a Yamaha R6 reg-rec to over-come this. if your reg-rec breaks it can fail in one of two ways..
i. it stops charging the battery so the battery doesnt get recharges and your bike is hard to start / runs badly until it stops alltogether.
ii. it over-charges the battery.. instaed of reducing the power from the generator it lets too much in.. this 'cooks' the battery and produces the same symptoms as case i. but it also kills the battery
So you need to test all 3 components of the electrical system Generator / Reg-Rec / Battery.
Electrexworld do a good step-by step guide for this that has been posted on here lots.
Cammo also has an excellent guide on replacing your reg-rec with an R6 unit if yours has died.
Spark Plugs
The nc30 uses small 8mm plugs.. there are very fragile and easy to kill so you must start the bike properly..when choke is required use full choke and no throttle until it is ticking over nicely.
ER10's shouldn't be the root cause of your problem. They are electrically equivalent to the 9's but are colder plugs, designed to run in a hotter engine.
The downside of these plugs is that unless you get the plugs up to an adequate temperature they won't clean propely and will foul up.
This will happen overtime if your not getting the engine hot enough but unlikely in such a short period, so it looks like you have flooded the engine which will kill any heat grade of plug.
I'd recommend using the correct range of plug though as it'll prevent longer term problems with starting and running.
So there you have it.
Until you've tested and verified all 3 sections are working / setup correctly it isn't going to run properly. This work shuold take a couple of days for a novice one day for an experienced mechanic.
Allow extra time to fit components if they failed.
or If you want me to make you any Cocktail i can 
