What is the proper etiquette when the marriage is the second for the groom in reqards to bridal showers and such

I don't know that there is a formal set of rules, but certainly it doesn't impact the bride wearing a bridal gown or anything relative to the ceremony. I think the only area of potential sensitivity is with the gifts. I would suggest that only very close relatives on his side of the family be invited to the showers - host them on the brides side (more common anyway).

Don't mention gifts (poor taste anyway) and please don't use those gift card enclosures in your invitation. You need to make a clear impression that you want people to be there for their company, not for a costly gift. Not mentioning gifts is the only way to really accomplish that properly.

You can still register. People will ask where you are registered, so you don't have to advertise. It will get around by word of mouth.

You might want to offset the expenses for groomsmen if the same men are standing up as in the second wedding. Perhaps the groom can cover all the tuxedo rentals, for example. Or ask different guys - family last time? Ask friends this time around, for example.

What is the proper etiquette when the marriage is the second for the groom in reqards to bridal showers and such
Wedding toasts

Not much difference except that you should be sensitive about the expenses you create for your friends and family on the groom's side. You might want to ask different guys to stand up for you, or if they've done it for the first wedding, offer to pay for the tuxedo rental or something of that kind. And I think it's kind of tacky to do the whole bachelor party thing... after a man's been married already, that's pretty immature (not that it isn't really immature and tacky for a first wedding!)

As for the bride, she should have her showers and white dress and her big day if she wants it. Nobody should take offense to that, certainly.