how tall should my plant be?.. and other questions

ok 4 things

1-do you count the flowering period from when you change the lights or when buds fird appear?

2-i have a super silver haze in the 4th week( or 2nd )of flowering and its about 4ft5inch tall
and a hymilayan gold at 4ft that was late in showing buds how tall should these guys be?

3- what does it mean when the new grow on your plant grows out yellow

4-how can you tell if your plant needs flushed?

this is my first time

hmmm #1 .. seed companys say from when you change the lights .. i always add a week ..
#2 .. stretch usually slows or stops after the 4th week of flowering .. but thats not written in stone .. keep the lights as close as you can without burning them .... but it is also dependent on the strain .. sativas are taller then indicas...
#3 not sure .. usually means its starving for nutes .. but im sure others will be able to tell you more
#4 i flush every 3rd watering .. but if you mean flushing before you take off your crop .. should be at least 2 weeks of flushing before the end .. ie .. if they are 9 week plants .. you should at least flush at 7 weeks .. even 6 1/2 for the rest of the grow

thanks tellno1 but i still need help

all the bottom leaves are yellow and the rest are lime green now cos no1s answering

thanks to the ppl who didnt help my plant are now dead

wow man sorry to hear of the loss ... but you have to agree you were asking some pretty vague questions .. pics and a little more about how you grow would have got you more answers from other growers, i did answer all your questions with the info you gave me .. ive had a lot of failures too .. just keep at it .. takes time to learn .. lots of ups and downs .. give all the info you can when asking questions .. find a grower to take you under their wing(so to speak) .. it all takes patience and time