Assuming the light bulb in your enlarger is about 75 watts (very common) and assuming your lens is stopped down to about f/8, and assuming you are enlarging 35mm to 8x10 size, AND assuming you are using #2 contrast filter, 20 seconds exposure should be around your starting point. If you are using no filters at all, 8 to 10 seconds should give you about the right exposure.

You don't need much developer. I use about 750cc in 8x10 tray. As long as you keep your paper covered and have enough to swish around, that's all you need.

Your safe light should be orange or red. Yellow may not work very well....

A quick test would be to take our a sheet of your paper, put some coins on it and let it sit in the room for 5 minutes or so. Then develop the sheet. If you can see the coin, it's not dark enough.