Carb issues?

Hey norm! This is my first thread, but I've been reading this forum for a few months now, since I started my first build. Its a Grubee Skyhawk GT-5 i believe with a 32:1 oil ratio, and a NT speed carb. Right now there's a few issues. first off, gas/oil is leaking from the head and from the muffler. Secondly, i believe there is probably an air leak. an issue i was having before was that it would start ok, however if a opened the throttle to quickly, the engine would just stop pushing the bike. I could get it up to high rpms, but i had to work the motor up to it slowly, every time. I would sometimes have to use the choke to get it rev normally again, which i know is not good. I decided to take a look inside the carb. I have the needle set to the second notch from the top. when i took the float bowl off, i noticed that the needle jet was sitting in the float bowl. I had never taken the bowl off before, so i am not entirely sure why it was there. The more perplexing issue is that when i tried to screw the needle jet back into the carb, it wouldn't thread into it, as if the threads are different. I seriously sat there for an hour just trying to get it to thread in, not forcing, just trying the get the threads to catch. It wouldn't. I've searched all over the forums and can't find anyone else with that issue. Frustrated, i tried to reassemble the carb so that i could at least get it running again. I was worried about the needle jet, but i got it so that the needle seemed to slide in and out of it despite it not being threaded into the carb. when i started it up, it sounded completely different. Kind of muffled. The idle is really weird and quiet. I don't know how else to describe it. the link to the video is actually just to give you an idea of what it sounds like. I just wanna get this thing running safely again before riding season is over.

motor sound - YouTube

p.s. sorry the pics are so zoomed in. i had to crop the heck out of them just to get them to upload.

Yeah i need to get my hands on a torque wrench. but what about the needle jet. my bike just stopped working the other day and was leaking gas through the air filter on the carb.

also, how does my plug look? am i running rich?

so i ordered another NT carb. this time the old version. I opened it up and just out of curiosity, I tried swapping out the needle jets. sure enough neither the new or old needle jets would thread correctly into the old carb and both threaded perfectly into the new carb. i installed the new carb and it fired right up. since then i have continued to notice that it doesn't idle quite right. it takes a while for it to return to low rpms after releasing the throttle and disengaging the clutch. also it bogged heavily at high mid to WOT. I bought some rtv and slathered up the manifold. the bogging has reduced greatly and now i can actually ride at WOT. top speed increased from around 21 to 27. however, it is still not a completely smooth ride up there due to what i think is slight bogging. Is this due to another leak? i pulled the spark plug after a test ride. is this too lean?

Also here's the link to video just for the audio of the test ride. audio kinda sucks but you can kinda hear how the WOT isn't perfectly smooth. when ever the sound waivers, the motors pull waivers.

http://www.youtube.com/watch?v=nqRqZykKEkA