Every month, couple days prior to haydh there is a very light brown discharge. I am not sure if this is slight istehadha and do i need to do wudhoo before every prayer?
Sometimes the discharge is continuous even during wudhoo time. Now that we have shabe barat, I don't know how to keep up with wudhoo? And after amals, I'm still in wudhoo, but discharge continues, do I need to make new wudhoo for namaze shab, quran etc?

Prior to haydh, the light brown discharge, if it has no continuity meaning it comes and goes, it will be considered istihadha and you have to follow the relevant rules for that in regards to wudhu and namaz etc.

However if it has continuity such as is similar during haydh, then it will be haydh.

During istihadha, there are three types, qaleel, mutawassit, Kathir.

If your istihadha is qaleel meaning little, then prior to namaz, you need to change your undergarments or sanitary pads etc if they have gotten dirty and do wudhu.