1. if I put a finely adjustable valve inline of the wastegate hose, does that act as a MBC? manual boost controller?

no. a mbc opens when a certain amount of pressure is built up behind it. or is it the other way around?

2. is there any sort of sound or other indication that my wastegate is infact working?

no. but if the mbc is set at a high enough amount of boost, you will know when it is working when you get thrown back in your seat. just be sure to put hose clamps on there. the first time i hooked up a mbc, the hose popped off. it's a good thing the car i was driving, volvo 740 turbo, has a computer cutoff at 15psi boost. also, bump your boost up in small increments. you don't want to blow the motor while just messing around. next thing to invest in is a big azz intercooler! i <3 boost.

3. would my boost gauge (when I get it) give more acurate readings tee'd off the wastegate line or driect in the manifold?

go off the manifold.