>1. Do save vs spell work against bard songs?

Some, yes. Others, no. Depends on the song.

>2. Do any resist(negative, mental and so on) aid against
>saving against a spell or is it only damage reduction?

Depends on the spell. There are some where it definitely helps, but as a general trend, just damage reduction.

>3. Can you use dubble vulns like silver/wrath against
>undead(if they even are vuln against both). Anyway if you find
>one will both increase damage or only one?

Not all undead will be vulnerable to both (in specific, I'm 95% sure that PC liches aren't) but in the case that they are, I believe both apply. This is based on my observations as a player and so is possibly incorrect.

>4. Lately some imms have just disappeared, forums gone and
>helpfiles gone also. Mind us throwing us a bone and perhaps
>some echoes what have happened?

Your guess is as good as mine. Someone else's department.