Firstly, the best UVB light to go for is the Arcadia T5's, you'll need a 10-12% and it should be 2/3-3/4 the length of the viv. If you need more advice have a look at the Arcadia website > Lighting Guide : Arcadia Reptile
< or PM Arcadiajohn on here.
The reason he might be freaking out at the UVB (especially if it is flickering) is that reptiles can see UVB - it flicking on and off, to them, could seem like a strobe light (I'm not a reptile but this is what I imagine it would be like
). Exo terra UVBs aren't that great so you're best changing it as soon as you can.
What are you taking the temperature measurements with? And do you have a thermostat on the bulb?
I think you should give him a little more time to settle in. 4-5 days isn't very long and he'll still be settling in, this will no doubt effect basking. It is a totally new environment for him and having a big beast (i.e. you) walking around and going near him is no doubt going to scare him. If it's particularly bad as you walk past him then perhaps a towel over the viv could help him feel more secure for the time being. Puffing out is very normal for young dragons that are stressed or threatened and trying to make themselves seem bigger.
Those basking temps might
need to be upped, however if he's currently not basking much I would leave them be.
On a side note remember to try to feed them a variety of foods - this will make for a healthier, more active beardy in the long run
Have to say it's nice to see someone that's obviously done their research and got their setup sorted out