Could this fly zipper Bug Zapper could be use in Baby room？

It can be used anywhere indoors. The arc is quite loud and could startle or wake a baby if that is your concern. Make sure children or pets cannot reach it. It is quite effective and keeps my house fly and mosquito free. Unless you keep the baby room door shut just placing it near the room should work as well.

How is the quality of the product? Is it workable for the mosquitoes?

Yes it works great with mosquitos. Please remember, this is an indoor unit, so putting it outside as major bug zapper isn't what it is designed for. We tried one night and while it worked and killed lots of different bugs (especially mosquitos) it gets a bit overwhelmed and totally filthy with lots of outdoor bugs.

Can this be used outside?

Until it rains. It would function properly but it's not suited for the elements. I wouldn't, and it specifically says "Indoor..."

Is this a 40 w bug zapper

The two UV lights which attract the bugs are T8 type 10W each, they are bright enough to shine the whole living room. The actual thing that zaps the bugs once they arrive to the device is a grid or mesh of wires with 2800 Volts, that is very powerful to zap any bug. The system is very good, and I do recommend it. Advice: when you unplug it to replace he UV tube, do not touch the inside grid, it takes time for the high voltage to discharge completely. Wait at least 2 hours as they say in the manual.