Help with Aplication Note 236 (Microchip)

Im trying to do the AN 236 with a few modifications but i have some serious doubts:


1_ What are the C and R (bleeding resistor) at the front end (where we detect the 120 khz) for exactly? Does the high reactive imp of the C down the value of the 220 v or how does it go down? The R is only to download the C in case of needing? After the R/C the value of 220 v is acceptable?

2_ After the parallel RC we have a high pass filter: I understand that i high pass filter is done with a C and a R where the Vout is through the R (thats why its put to ground......what a dont understand is why before the C there is an R of 10k and after the 33k R to ground there is another C (150pF) with same value as the one before..........(if you see the circuit from AN236 youll get it)?

3_ How does the inverter in mode amplifier (with R in parallel ) work?dont understand how it amplifis...i know it does cause of datasheet ..but theoretical how does it happen........and in the amplification stage untuned
what are the C (10pF) for???

4_ Can someone explain me well how that envelope detector works!!!!!!how does the signal (120khz) pass through the diode?????why is it turned around???I imagine that this last part is to have -5v always to the pic and +5 when the carrier 120khz is present...but how does this happen in detail?????
5-The zero cross detector in 16F84 is made with just a R connected to RB0.....can this really be connected directly to 220 v?????? How do I make with that a cross detector??do i have to program it??does the pic have a cross detector in RBO ?really dont get it......(i just have to configure INTCON
register??)

6-Going to use the pwm module of pic 16F628A to control a triac for an inductive load..any examples on how its used???

7-Any ideas on how to use a switch with this project so i can select which house and unit code to use???

Thanks a lot for at least reading this ..see you soon.