If you don't want to invite your parents to a wedding don't tell them about the wedding in the first place.
It's not in most cases. Destination weddings may be an exception, but to invite someone to your shower and not your wedding is a big no no.
Widowed mothers and fathers can escort their children alone.
No, it's rude to invite a guest to the Engagement Party when you have no intention of asking them to the wedding. If the guest has a reason they can't make the wedding then it's just fine to invite them to the Engagement Party.
No. You can invite or refuse to invite anyone you wish.
* It is wise not to invite 'some' subordinates' lest you hurt others feelings. If you have close friends that are your subordinates then you can invite them to the wedding.
You are cordially invited to attend my wedding.
There are no "signs" in a Jewish wedding.
With difficulty.
A kittel is a simple white tunic worn by Jewish men at certain events including their wedding and during Yom Kippur. It is also what the deceased are buried in.
The correct preposition to use with the word "invite" is "to." For example: "I invited my friends to the party."
jacob